METHOD AND SYSTEM FOR DETERMINING A QUALITY PARAMETER OF A REPRESENTATION OF A COATING COMPOSITION

Abstract

Disclosed herein are a method and a system for determining a quality parameter of a representation of a coating composition. More specifically, disclosed herein is a method of determining a quality parameter of a modified or new representation of a coating composition, such as a mixing formula, by acquiring sensor data during application of the coating composition as well as surface property data of the prepared coating layer and comparing said data to predefined values, in particular predefined parameters and/or tolerances. The methods disclosed herein may be used for screening modified or new representations of coating compositions according to a quality criterion as well as a database including at least one modified or new representation of a coating composition, where the modified or new representation is provided to the database using the disclosed method.

Claims

1. A process for determining a quality parameter of a representation of a coating composition, said method comprising the steps of: (i) providing a modified or new representation of a coating composition; (ii) preparing the coating composition from the provided modified or new representation; (iii) producing a coating layer on at least a part of a substrate by manually applying the coating composition prepared in step (ii) with a spray gun comprising a sensor unit, a processing unit and optionally a signal unit to at least part of the substrate while acquiring sensor data with the sensor unit; (iv) optionally providing feedback to a user via the signal unit during manual application of the coating composition based on the sensor data acquired in step (iii); (v) optionally repeating steps (i) to (iii) or steps (i) to (iv); (vi) providing to a computer processor via a communication interface at least a part of the sensor data acquired in step (iii); (vii) providing to the computer processor via the communication interface surface property data of at least one coating layer produced in step (iii); (viii) determining with the computer processor at least one quality parameter of at least one representation provided in step (i) based on the sensor data provided in step (vi), and the surface property data provided in step (vii); (ix) providing via the communication interface the at least one quality parameter determined in step (viii); and (x) providing the representation of the coating composition via the communication interface to at least one database if the quality of said representation is determined in step (viii) to be acceptable.

2. The process according to claim 1, wherein providing the modified or new representation of the coating composition may include providing a modified or new mixing formula or a modified or new recipe.

3. The process according to claim 1, wherein the sensor unit includes at least one sensor.

4. The process according to claim 3, wherein the at least one sensor is selected from the group consisting of distance sensors, orientation sensors, acceleration sensors, LiDAR sensors, pressure sensors, paint flow rate sensors, temperature sensors, humidity sensors, and combinations thereof.

5. The process according to claim 1, wherein the sensor data acquired in step (iii) is selected from the group consisting of data on the distance between the spray gun and the substrate, data on the orientation of the spray gun with respect to the substrate, data on the movement of the spray gun, data on the contour of the substrate, data on the pressure of the compressed air, data on the flow of the coating composition, temperature data, humidity data and combinations thereof.

6. The process according to claim 1, wherein providing feedback to a user during manual application of the coating composition with the spray gun in step (iv) includes providing the sensor data acquired in step (iii) via a communication interface to the processing unit of the spray gun, processing with the processing unit the provided sensor data to determine whether the provided data is within or outside at least one predefined value, and providing with the signal unit at least one signal to the user in response to the processed sensor data.

7. The process according to claim 1, wherein providing surface property data in step (vii) includes determining surface property data of at least one coating layer applied in step (iii) and providing the determined surface property data to the computer processor via the communication interface.

8. The process according to claim 1, wherein determining the quality of the provided modified or new representation of the coating composition in step (viii) includes providing at least one predefined application value, and at least one predefined surface property value, via a communication interface to the computer processor and determining with the computer processor if the sensor data provided in step (vi) is within at least one predefined application value, and if the surface property data provided in step (vii) is within at least one predefined surface property value.

9. The process according to claim 1, wherein the quality parameter is a classifier being indicative of the acceptability of the provided modified or new representation of the coating composition.

10. The process according to claim 9, wherein the quality of the provided modified or new representation of the coating composition is acceptable if the sensor data provided in step (vi) is within at least one predefined application value and if the surface property data provided in step (vii) is within at least one predefined surface property value.

11. The process according to claim 1, further including the steps of (x) analyzing with the computer processor sensor data provided in step (vi); and/or (xi) optionally providing recommendations via the communication interface if the sensor data provided in step (vi) and/or the surface property data provided in step (vii) is outside of predefined value(s); and/or (xii) generating a further representation if the sensor data provided in step (vi) and/or the surface property data provided in step (vii) is outside of at least one predefined value.

12. A system for determining a quality parameter of a representation of a coating composition, said system including: a) means for providing at least one modified or new representation of the coating composition; b) a spray gun for manually applying the coating composition to a substrate, the spray gun comprising a sensor unit for acquiring sensor data during operation of the spray gun, a processing unit for processing the acquired sensor data and optionally a signal unit for providing at least one signal in response to the processed sensor data: c) at least one communication interface; d) means for providing surface property data of at least one coating layer produced from the provided representation of the coating formulation; and e) means for determining at least one quality parameter of the provided modified or new representation of the coating composition.

13. The method of claim 1 further comprising screening representations of coating compositions according to a quality criterion.

14. A system comprising a) a modified or new representation of a coating composition, and b) a quality parameter, wherein the quality parameter is determined according to the method of claim 1.

15. A database comprising at least one modified or new representation of a coating composition, wherein the modified or new representation of the coating composition is provided to the database according to the method of claim 1.

16. The process according to claim 1, wherein providing feedback to a user during manual application of the coating composition with the spray gun in step (iv) includes providing the sensor data acquired in step (iii) via a communication interface to the processing unit of the spray gun, processing with the processing unit the provided sensor data to determine whether the provided data is within or outside at least one predefined parameter and/or tolerance, and providing with the signal unit at least one signal to the user in response to the processed sensor data.

17. The process according to claim 1, wherein determining the quality of the provided modified or new representation of the coating composition in step (viii) includes providing at least one predefined application parameter and/or tolerance, and at least one predefined surface property parameter and/or tolerance, via a communication interface to the computer processor and determining with the computer processor if the sensor data provided in step (vi) is within at least one predefined application parameter and/or tolerance, and if the surface property data provided in step (vii) is within at least one predefined surface property parameter and/or tolerance.

18. The process according to claim 9, wherein the quality of the provided modified or new representation of the coating composition is acceptable if the sensor data provided in step (vi) is within at least one predefined application value and if the surface property data provided in step (vii) is within a set of predefined application and surface property values.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0213] These and other features of the present invention are more fully set forth in the following description of exemplary embodiments of the invention. To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced. The description is presented with reference to the accompanying drawings in which:

[0214] FIG. 1 illustrates a spray gun comprising a sensor unit, a processing unit and a signal unit which is used in the inventive method

[0215] FIG. 2a is a block diagram of a method for determining a quality parameter of a representation of a coating composition, such as a mixing formula

[0216] FIG. 2b is a block diagram of a preferred embodiment of the inventive method

[0217] FIG. 3 illustrates a system in accordance with the invention

DETAILED DESCRIPTION

[0218] The detailed description set forth below is intended as a description of various aspects of the subject-matter and is not intended to represent the only configurations in which the subject-matter may be practiced. The appended drawings are incorporated herein and constitute a part of the detailed description. The detailed description includes specific details for the purpose of providing a thorough understanding of the subject-matter. However, it will be apparent to those skilled in the art that the subject-matter may be practiced without these specific details.

[0219] FIG. 1 depicts a schematic illustration of a spray gun 100 operable to manually apply a coating composition to a substrate. In this example, the spray gun 100 is a pneumatic spray gun operably to apply a liquid coating composition to the substrate. In another example, the spray gun 100 may be an electrostatic spray gun. In yet another example, the coating composition may be a powder coating composition. The spray gun 100 comprises a body 102 having a spray nozzle 104. Connected to the body is a trigger 106, a reservoir 108 comprising the coating composition and means 110 to deliver the coating composition to the substrate. In this example, reservoir 108 is shown as a single item for the sake of simplicity. In another example, the spray gun 100 may typically be configured so as to be provided with separate reservoirs 108.1 to 108.n and means 110.1 to 110.n to deliver the coating compositions being present in the reservoirs 108.1 to 108.n. In this example, the means 110 is compressed air. In another example, the means 110 is a combination of compressed air and electricity. When the trigger 106 is pressed by an operator, such as a painter in a repair shop, the coating composition being present in reservoir 108 is applied to the substrate by means 110. The spray gun 100 further comprises a sensor unit 112, a processing unit 114 and a signal unit 116. In this example, the processing unit 114 is a microprocessor. In this example, the sensor unit 112, the processing unit 114 and the signal unit 116 are configure as a single unit being attached to the body 102 of the spray gun 100. In another example, the processing unit 114 and/or the signal unit 116 may be attached separately from the sensor unit 112 to the body 102 of the spray gun 100.

[0220] FIG. 2a depicts a non-limiting first embodiment of the inventive method 200 of determining the quality of a representation of a coating composition. In this example, a refinish basecoat composition and a refinish clearcoat composition are prepared and are applied subsequently onto a defective area of a multilayer coating of an automotive after sanding and optionally further pretreatment of the defective area.

[0221] In block 202, routine 201 determines whether the user wants to develop a new mixing formula, such as a new mixing formula for a refinish basecoat composition. For this purpose, routine 201 may display a menu on a GUI of a display device prompting the user to make the appropriate selection. The display device may be connected to personal computer comprising a computer processor or may be included in a mobile device, such as a smartphone, tablet or laptop, comprising a computer processor. In case the user wants to develop a new mixing formula, routine 201 may display recommendations on the screen which support the user in the development or may initiate an application or tool designed to develop new mixing formulae as described later on. Method 200 then proceeds to block 214 described later on. In case the user does not want to develop a new mixing formula, routine 201 proceeds to block 204.

[0222] In block 204, the user needs to provide properties of a multilayer coating, such as the color and/or appearance, the VIN, a color code, a mixing formula used to prepare a refinish basecoat composition etc. . . . For this purpose, routine 201 may display a menu on a GUI of the display device containing available options for retrieving existing mixing formulae of refinish basecoat compositions. Depending on the user selection, routine 201 may display further menus guiding the user through the data entry process necessary to retrieve the mixing formula as described in relation to block 206. The color and/or appearance of the multilayer coating may be provided by measuring the color and/or appearance of the multilayer coating of the automotive at undamaged site(s) with a commercially available spectrophotometer or by inputting color values associated with the multilayer coating. The acquired data may either be processed by the spectrophotometer or the computer processor. The processed data or the acquired raw data is provided to a computer processor via a communication interface, such as a USB cable or a wireless communication interface. The color code can be provided by visually comparing color chips with the undamaged multilayer coating and entering the color code associated with the best matching color chip.

[0223] In block 206, the properties provided in block 204 are used to retrieve suitable existing mixing formulae from a database connected via a communication interface, such as the internet, to the computer. The database contains existing mixing formulae associated with properties, such as the color and/or appearance, the VIN, the color code, mixing formula for matching clearcoats/basecoats or a combination thereof. In one example, a refinish clearcoat composition is selected upon repeating blocks 202 to 208 from a database based on the properties of the refinish basecoat composition provided in the first run of blocks 202 to 208. For this purpose, routine 201 may use the mixing formula selected in block 208 to retrieve suitable refinish clearcoat compositions from the database based on the selected mixing formula. In another example, routine 201 may display on the screen of the display device a list of available refinish clearcoat compositions.

[0224] In block 208, the user selects an appropriate mixing formula from the existing mixing formulae retrieved in block 206 and the selected mixing formula is displayed on the screen of the display device. Displaying the selected mixing formulae may include displaying further data, for example comments, rankings, a price, etc. which may be retrieved from a database based on the mixing formulae retrieved in block 206.

[0225] In block 210, routine 201 determines whether the user wants to modify the selected mixing formula. For this purpose, routine 201 may display a menu on a GUI of the display device prompting the user to make the appropriate selection. If the user wants to modify the selected mixing formula, method 200 proceeds to block 212. Otherwise, method 200 proceeds to block 216.

[0226] In block 212, the user modifies the selected mixing formula by changing the weight ratio of the tinting base, unpigmented base and reducer base listed in the mixing formula as desired. In one example, the modification of the existing representation may be performed after preparing a test panel and comparing the visual appearance of the test panel with the visual appearance of the coating at undamaged site(s). The modified mixing formula may be provided to the processor of the personal computer or mobile device, for example via a communication interface. This may be beneficial if an automated weighing apparatus is used in block 216 as described later on.

[0227] In block 214, the user develops a new mixing formula. This may include defining parameters, such as amounts, ratios, production parameters, etc. without using an existing mixing formula as a basis. Development of a new mixing formula may be performed using an application or tool. In one example, the application or tool may comprise a simulation or prediction function which can predict whether the developed mixing formula provides the desired surface properties to support the development. In another example, the application or tool can provide a newly developed mixing formula based on provided data, such as surface property data. The newly developed mixing formula may be provided to the processor of the personal computer or mobile device, for example via a communication interface, in case the application or tool is not run on said personal computer or mobile device. This may be beneficial if an automatic weighing apparatus is used in block 216 as described in the following.

[0228] In block 216, the refinish basecoat composition is prepared from the mixing formula selected in block 208 or the modified mixing formula prepared in block 212 or the mixing formula newly developed in block 214, by mixing the tinting base, the unpigmented base and the reducer base in the amounts listed in the selected/modified/newly developed mixing formula and stirring the obtained coating composition. Mixing may be performed by transferring the mixing formula in digital form to an automated weighing apparatus which performs the weighing operation based on the transferred data and optionally stores the result of the weighing operation for further quality control checks. For this purpose, the weighing apparatus is connected via a communication interface to the computer processor previously described.

[0229] In block 218, routine 201 determines whether the user wants to receive feedback from the sensor unit of the spray gun during application of the coating composition prepared in block 216. For this purpose, routine 201 may display a menu on a GUI of the display device prompting the user to make the appropriate selection. If routine 201 determines that the user wants to receive feedback during the application process, routine 201 proceeds to block 222. Otherwise, method 200 proceeds to block 220.

[0230] In block 220, a coating layer is produced on the defective sites of the multilayer coating by manually applying the coating composition prepared in block 216 with a spray gun comprising a sensor unit, a processing unit and a signal unit to the defective site while acquiring sensor data with the sensor unit. The applied coating layer is afterwards dried and/or cured. A spray gun for manually applying the coating composition to the substrate and being suitable for use in block 220 is described, for example, in relation to FIG. 1. During manual application of the coating composition, sensor data is acquired with the sensor unit of the spray gun. The sensor data acquired during the manual application of the coating composition may be stored on the internal storage of the processing unit prior to providing the acquired sensor data to a further computer processor as described in relation to block 232.

[0231] In block 222, routine 201 provides to the processing unit of the spray gun predefined application values via a communication interface, such as Bluetooth or WiFi to the processing unit of the spray gun. In this example, the following values were provided: a distance value, i.e. tolerance for the distance between the spray gun and the substrate, and an orientation value, i.e. a tolerance for the orientation of the spray gun with respect to the substrate, a movement value and a pressure value, i.e. a tolerance for the pressure of the compressed air, a flow value, i.e. a tolerance for the flow of the basecoat composition, a temperature value and a humidity value. In another example, at least one of the aforementioned values is provided by routine 201 to the processing unit. In one example, the values provided by routine 201 to the processing unit are retrieved by routine 201 from a database based on the mixing formula selected in block 208. This may be preferred if a selected or modified mixing formula is used to prepare the coating composition in block 216. In another example, the user may input appropriate application values or may select appropriate application values from a list of available application values. Routine 201 detects the user input, converts the user input to the respective application values and provides the values via the communication interface to the processing unit of the spray gun. Routine 201 may be programmed to store the retrieved or converted values on the internal memory of the device for later use, such as described in relation to block 240 later on.

[0232] In block 224, a coating layer is manually produced on the defective sites of the multilayer coating by applying the coating composition prepared in block 216 with a spray gun as described in relation to block 220.

[0233] In block 226, the processor of the processing unit of the spray gun determines whether the sensor data acquired in block 224 is outside of at least one application value provided in block 222. In case the acquired sensor data is outside of at least one provided application value, block 228 is performed. Otherwise, method 200 proceeds to block 230.

[0234] In block 228, the processing unit controls the signal unit in response to the determination performed in block 226. Said signal unit provides at least one signal, for example by changing the color of the optical signal and/or changing the sound of the acoustic signal and/or changing the intensity of the haptic signal, in response to the control by the processing unit. This allows to provide feedback to the user of whether the application conditions used to manually apply the coating composition in block 224 are within predefined application values, thus ensuring that the coating composition is applied under standard application conditions to prevent a color mismatch due to the use of non-standard application conditions associated with the respective mixing formula. To provide feedback on the application conditions in real time to the user, blocks 224 to 228 are preferably performed simultaneously. Simultaneously refers to the time it takes the sensor unit to acquire the sensor data and the processing unit to process the sensor data (i.e. to determine whether the acquired data is within or outside of provided predefined application values) and to control the signal unit based on the processing result.

[0235] In block 230, routine 201 determines whether the user wants to apply a further coating composition. If this is the case, routine 201 proceeds to block 202, otherwise, routine 201 proceeds to block 232.

[0236] In block 232, the sensor data acquired in blocks 220 and/or 224 is provided to at least one computer processor via a communication interface. The sensor data includes the sensor data obtained during application of the basecoat composition in block 220 or 224 and the sensor data obtained during application of the clearcoat composition to the substrate upon repeating block 220 or 224. In this example, the computer processor is included in the personal computer, a laptop or a mobile communication device, such as a smartphone or tablet, described in relation to block 202. In another example, the sensor data is retrieved by routine 201 and provided via the communication interface to a cloud environment. The retrieved sensor data may be displayed on the screen of the display device.

[0237] In block 234, routine 201 retrieves surface property data of the prepared coating layer(s) and provides the retrieved data to the computer processor. In this example, surface property data is retrieved by routine 201 after the clearcoat layer applied in block 220 or 224 was cured. For this purpose, color data and/or appearance data and/or gloss data is obtained by measuring the color and/or appearance and/or the gloss of the prepared multilayer coating with a multi-angle spectrophotometer and/or a gloss meter. The spectrophotometer and/or gloss meter is each connected via a communication interface to the at least one processor and the acquired or preprocessed data is retrieved by routine 201 and provided to the at least one processor via said communication interface. The communication interface can be wireless, such as Bluetooth or WiFi, or wired, for example by use of a USB cable or ethernet.

[0238] In block 236, routine 201 determines whether the quality parameter is to be determined for each mixing formula associated with the coating composition applied in block(s) 220 or 224. Routine 201 may be programmed to proceed automatically to block 240 in case block 220 or 224 is only performed once, i.e. only one coating composition is applied to the substrate. In case at least 2 coating compositions were subsequently applied, i.e. block 220 or 224 was repeated at least twice, routine 201 may display a menu on a GUI of the display device prompting the user to make the appropriate selection. If routine 201 determines that the user wants to obtain the quality parameter for selected mixing formula(e), routine 201 proceeds to block 238. Otherwise, routine 201 proceeds to block 240 described later on.

[0239] In block 238, routine 201 detects a user input associated with selecting a mixing formula(s) from the list of mixing formula(e) used in block 216. For this purpose, routine 201 may display a list on a GUI of the display device comprising all mixing formula(e) used in block 216 and may detect the selection(s) made by the user. Routine 201 then proceeds to block 240.

[0240] In block 240, routine 201 retrieves predefined surface property value(s) and optionally predefined application value(s) and provides the retrieved value(s) to the processor. The predefined application values only need to be retrieved if block 222 was not performed or if the application values retrieved in block 222 were not stored on the internal memory of the device. In one example, the value(s) are retrieved by routine 201 from at least one database based on the mixing formula selected in block 208 or based on a mixing formula selected by the user from a list of available mixing formula. In another example, the value(s) is/are provided by the user via a GUI by manual input or by import from a file.

[0241] In block 242, a quality parameter for each mixing formula(e) or for each selected mixing formula(e) is determined with the processor based on the sensor data provided in block(s) 220 or 224 and the surface property data provided in block 234. The quality parameter is a classifier being indicative of the acceptability of the mixing formula modified in block 210 or newly developed in block 214. The quality parameter is obtained by determining whether the sensor data provided in block(s) 220 or 224 is within predefined application value(s) and the surface property data provided in block 234 is within predefined surface property value(s). The predefined application value(s) may include distance value(s), orientation value(s), movement value(s), pressure value(s), flow value(s), temperature value(s), humidity value(s) or any combination thereof. In this example, the predefined application values include distance value(s), orientation value(s) and movement value(s). The value(s) can be the same for the application of the basecoat composition and the clearcoat composition or can be different. In this example, the predefined surface property value(s) is/are predefined color tolerances, such as ?L*, ?C*, ?h* or ?L*, ?a*, ?b*, predefined appearance value(s), predefined gloss value(s) and combinations thereof.

[0242] In block 244, the quality parameter(s) determined in block 240 is/are provided by routine 201 via the communication interface and are displayed on the screen of the display device. In this example, the quality parameter(s) is/are a classifier indicating the acceptability of the modified or newly developed mixing formula. In one example, the classifier can be suitable quality or non-suitable quality. In this example, the provided sensor data, surface property data and the predefined value(s) used for the determination are also displayed to the user. In another example, only the determined quality parameter(s) is/are displayed. In one example, the displayed data may be colored to visualize deviations from the predefined value(s).

[0243] In block 246, routine 201 determines whether the quality of the mixing formula(e) is/are acceptable, i.e. whether acquired sensor data is within predefined application value(s) and whether the determined surface property data is within predefined surface property value(s). For this purpose, routine 201 may check the result of block 242 and proceeds to block 248 in case the quality of the modified/new mixing formulae is OK. Otherwise, routine 201 proceeds to block 254 described later on.

[0244] In block 248, the modified mixing formula generated in block 210 or the new mixing formula developed in block 214 is provided via the communication interface to at least one database. The database already contains existing representations, in particular existing mixing formulae, in connection with further information, such as color values, VIN etc. In this example, the modified/new mixing formula(e) is/are provided to the database by manual input or by importing the representation being stored on a computer readable medium. Apart from the mixing formula(e), further data, such as surface property data provided in block 234, comments, etc., may also be provided to the database and are stored in combination with the provided modified/new mixing formula(e). The user may get a notice stating that the modified or new representation has been provided to the database after manual input or import.

[0245] FIG. 2b depicts a second non-limiting embodiment of the inventive method 200 of determining the quality of a representation of a coating composition. In this example, a refinish basecoat composition and a refinish clearcoat composition are prepared and are applied subsequently onto a defective area of a multilayer coating of an automotive after sanding and optionally further pretreatment of the defective area.

[0246] Method 200 of comprises blocks 202 to 248 previously described in relation to FIG. 2a. Additionally, method 200 includes blocks 250 to 260 as described in the following. Method 200 may be performed if the user wants to analyze the sensor data provided in block 232 of FIG. 2a or if the user wants to generate modified mixing formula(e) based on his personal application parameters (i.e. the acquired sensor data) which provides a better match in terms of visual appearance than the mixing formulae used to prepare the coating composition in block 216 of FIG. 2a.

[0247] In block 250, routine 201 determines whether to analyze the provided sensor data. For this purpose, routine 201 may display a menu on a GUI of the display device prompting the user to make the appropriate selection. If routine 201 determines that the user wants to analyze the acquired sensor data, routine 201 proceeds to block 252. Otherwise, routine 201 proceeds to block 254 described later on.

[0248] In block 252, the sensor data provided in block 232 of FIG. 2a is analyzed with a computer processor. The processor may be included in a personal computer or laptop, a mobile communication device or a cloud application. In case the data is not yet available to the processor, routine 201 retrieves the data from the respective data storage medium and provides the data to the processor. The processor analyses the data gathered from the distance sensor, the orientation sensor and the movement sensor and the result of the analysis is displayed via a communication interface, preferably a display comprising a GUI, to the user. In one example, the displayed analysis includes movement patterns being displayed graphically to increase user comfort. In a further example, the displayed analysis further includes standard movement patterns to visualize any deviations. The standard movement patterns can be generated using the predefined application value(s) retrieved in block 222 or 240 of FIG. 2a. In yet another example, the displayed analysis includes graphical representations, such as bar charts, depicting the allowable range/value and the determined sensor data/surface property data.

[0249] In block 254, routine 201 determines whether to display at least one recommendation on the screen of the display device. For this purpose, routine 201 may check the result of block 246 or 242 or may display a GUI prompting the user to make the appropriate selection and proceeds to block 256 in case the at least one recommendation is to be displayed. Otherwise, routine 201 proceeds to block 258 described later on

[0250] In block 256, routine 201 displays at least one recommendation on the screen of the display device. Routine 201 may retrieve the recommendations from a database based on the result of the determination performed in block 242 of FIG. 2a and provides the retrieved recommendation(s) to the processor. In one example, the recommendation may be in the form of a text message, such as Distance of spray gun during application of coating material not ok. Repeat spraying process using the correct distance to obtain better results. In another example, the recommendation may be in the form of a graphical representation.

[0251] In block 258, routine 201 determines whether the user wants to modify the mixing formula(e) developed in block 214 of FIG. 2a or the modified mixing formula(e) generated in block 210 of FIG. 2 such that the desired surface properties are obtained. For this purpose, routine 201 may display a menu on a GUI of the display device prompting the user to make the appropriate selection. If routine 201 determines that the user wants to modify the mixing formula(e), routine 201 proceeds to block 260. Otherwise, routine 201 ends method 200 or proceeds to block 202 of FIG. 2a.

[0252] In block 260, a further modified mixing formula(e) is/are generated if the sensor data provided in block 232 of FIG. 2a and/or the surface property data provided in block 234 of FIG. 2a is/are outside of at least one predefined value, i.e. if the quality of the mixing formula developed in block 214 of FIG. 2a or the mixing formula modified in block 210 of FIG. 2a is determined to be not acceptable. The following method is used in block 260 to determine modified mixing formula(e): [0253] optionally providing the mixing formula(e) of block 210 or 214 of FIG. 2a and surface property data of block 234 of FIG. 2a via a communication interface to a computer processor, [0254] providing via a communication interface to a computer processor a target color of a coating layer, [0255] optionally retrieving with the computer processor via the communication interface from a database specific optical data of individual color components associated with the mixing formula(e) of block 210 or 214 of FIG. 2a, [0256] providing via the communication interface to the computer processor a numerical method and a physical model, wherein the numerical method is configured to optimize application adaption parameters by minimizing a given cost function starting from a given set of initial application adaption parameters, the given cost function being particularly chosen as a color difference between the provided surface property data and predicted surface property data of the mixing formula(e) of block 214 or 210 of FIG. 2a, and the physical model is configured to predict the color of the mixing formula(e) of block 214 or 210 of FIG. 2a by using as input parameters the color formulation associated with the mixing formula(e) of block 214 or 210 of FIG. 2a and the retrieved specific optical data of the individual color components and respective preliminary application adaption parameters resulting in the course of optimization, calculating with the computer processor application adaption parameters using the [0257] provided numerical method and the physical model by comparing the recursively predicted color of the mixing formula(e) of block 214 or 210 of FIG. 2a with the provided surface property data until the given cost function falls below a given threshold, [0258] calculating using the provided target color and calculated application adaption parameters as input parameters for the paint color formulation calculation algorithm, a modified representation with optimized concentrations of individual color components as target color formulation for a target paint coating when the target paint coating is applied on a substrate using the sensor data acquired in block(s) 222 or 224 of FIG. 2a, and [0259] providing the modified mixing formula(e) via a communication interface.

[0260] In this example, the generation of the modified mixing formula(e) is performed on further computer processor(s), i.e. computer processors being separate from the computer processor performing block 242 of FIG. 2a. These computer processor(s) may be located on a stationary computing device or in a cloud environment. The mixing formula(e) of blocks 210 or 214 of FIG. 2a as well as the surface property data provided in block 234 of FIG. 2a is provided to the computer processor(s) via a communication interface. In this example, data on the target color is determined in block 204 of FIG. 2a. In another example, the target color is retrieved by the computer processor(s) from database based on the mixing formula selected in block 208 of FIG. 2a

[0261] In this example specific optical data of individual color components is retrieved from a database with the processor(s) based on the mixing formula(e) of blocks 214 or 210 of FIG. 2a. In another example, this data is stored on a data storage medium, such as an internal storage.

[0262] The numerical method and physical model used for calculation of the application adaption parameters previously described as well as the paint color formulation calculation algorithm previously described is either implemented on the computer processor(s) or is retrieved from a database.

[0263] In this example, the calculated modified representation is displayed on the screen of a display device such that the user can prepared a modified coating composition based on the displayed information. The calculated modified representation may be interrelated with the sensor data acquired in block 220 or 224 of FIG. 2a and may be stored in a database.

[0264] FIG. 4 shows an example of a system 436 for determining a quality parameter of a representation of a coating composition comprising: [0265] means for providing at least one representation of the coating composition 402; a spray gun 404 for manually applying the coating composition to a substrate, the spray gun 404 comprising a sensor unit 406 for acquiring sensor data during operation of the spray gun, a processing unit 408 for processing the acquired sensor data and a signal unit 410 for providing at least one signal in response to the processed sensor data; a communication interface 412, 414, 416, 418, 420, 422, 424; means for providing surface property data of at least one produced coating layer 426; a computer processor 428 and a memory 430 storing instructions, that when executed by the processor, configure the system to perform the steps of: [0266] providing to the computer processor via the communication interface at least part of the sensor acquired sensor data; [0267] providing to the computer processor via the communication interface surface property data of at least one produced coating layer; [0268] determining with the computer processor at least one quality parameter of at least one representation based on the provided sensor data and the provided surface property data; and [0269] providing via the communication interface the at least one determined quality parameter.

[0270] In this example the system further comprises an input/output device 432. In this example, existing representations of coating compositions are stored in database 402. The existing representations are mixing formulas for preparing refinish basecoat and clearcoat compositions. The database is connected via communication interface 412 with the input/output device 430. The user retrieves an existing representation for preparing a basecoat composition via input/output device 430 from database 402 and modifies this representation, for example by changing the weight ratio of the components listed in the mixing formula. The modified mixing formula is stored by the user on a computer readable storage medium. The storage medium can be a memory of the input/output device or a database or a cloud application connected via a communication interface to the input/output device. The coating composition is prepared from the modified mixing formula and is manually applied on the substrate with spray gun 404 while acquiring sensor data with sensor unit 406. In this example, feedback is provided to the user during manual application of the coating composition by providing the acquired sensor data to processing unit 408 of the spray gun via communication interface 414. The processing unit 408 determines whether the acquired sensor data is within predefined value(s) and controls signal unit 410, which provides optic, acoustic or haptic signals in response to the control by the processing unit. The predefined value(s) are provided by input/output device 432 via communication interface 416 to the processing unit 408 prior to application of the coating composition to the substrate. The sensor data acquired during manual application of the coating composition is provided to processor 428 via communication interface 418. In this example, means for providing surface property data 426 include a multi-angle spectrophotometer and/or a gloss meter. The multi-angle spectrophotometer and/or gloss meter are connected via communication interface 420 to computer processor 428. The input/output device 432 is used to provide application value(s) and surface property value(s) to the processor 428 via communication interface 422. The application value(s) and surface property value(s) are stored in database 434, which is connected via communication interface 424 to input/output device 432. With the computer processor 428, the quality parameter, in this example the suitability of the modified representation(s) with respect to achieving the desired surface properties, such as color and/or appearance and/or gloss, are determined based on the sensor data provided via communication interface 418, the surface property data provided via communication interface 420 and the value(s) provided from database 434 via communication interface 424. In this example the determined quality parameter is provided to the input/output device 432 via communication interface 422. If the quality of the adapted representation(s) is acceptable, the adapted representations are provided via input/output device 432 and communication interface 412 to database 402.