Definition & Meaning
A Wet Film Thickness (WFT) worksheet is a crucial tool in the coatings industry, designed to assist applicators in measuring and recording the thickness of wet paint layers. This worksheet ensures that the final dried coating achieves the specified Dry Film Thickness (DFT), which is essential for the coating's performance and durability. The WFT worksheet typically includes fields for recording measurements taken with a notched gauge, calculations based on the wet film thickness formula, and notes on application techniques. By maintaining accurate records, applicators can ensure compliance with project specifications and industry standards.
How to Use the WFT Worksheet
Using a WFT worksheet involves several key steps to ensure accurate measurements and compliance with specifications. First, determine the target WFT based on the coating's solids-by-volume percentage and the required DFT. The formula to calculate WFT is:
WFT = DFT / (Solids by Volume %)
Next, apply the coating and use a notched WFT gauge to measure the wet film thickness immediately after application. Record the highest tooth that is coated and the next uncoated tooth. The WFT lies between these two values. Log this reading on the worksheet, and if adjustments are necessary, modify the application technique accordingly before re-measuring.
Key Elements of the WFT Worksheet
Essential components of a WFT worksheet include:
- Date: The date of application and measurement.
- Project Name: Identification of the specific project.
- Coating Type: Details about the coating being applied.
- Measured WFT: The actual wet film thickness recorded during application.
- Target WFT: The calculated wet film thickness based on project specifications.
- Notes: Any observations or adjustments made during the application process.
Examples of Using the WFT Worksheet
Consider a scenario where a contractor is applying an epoxy coating that requires a DFT of eight mils. The manufacturer's data indicates a solids-by-volume percentage of fifty percent. Using the wet film thickness formula, the contractor calculates the target WFT:
WFT = 8 mils / 0.50 = 16 mils
After applying the coating, the contractor uses a notched gauge and finds that the WFT is between 15 and 17 mils. This measurement is logged in the worksheet, and adjustments are made to the spray technique to ensure the target range is achieved consistently.
Why Should You Use the WFT Worksheet?
The WFT worksheet is vital for several reasons:
- Performance Assurance: It helps ensure that critical properties, such as fire resistance and corrosion protection, are achieved.
- Quality Control: The worksheet validates that the application meets the specified thickness, reducing the risk of failures.
- Cost Efficiency: By preventing over-application or under-application, the worksheet helps minimize waste and associated costs.
Who Typically Uses the WFT Worksheet?
The WFT worksheet is commonly used by various professionals in the coatings industry, including:
- Contractors: Those responsible for applying coatings on construction projects.
- Quality Control Inspectors: Individuals who verify that coatings meet specified standards.
- Manufacturers: Companies that produce coatings and require adherence to application guidelines.
Steps to Complete the WFT Worksheet
Completing a WFT worksheet involves the following steps:
- Calculate Target WFT: Use the wet film thickness formula based on DFT and solids-by-volume percentage.
- Apply Coating: Ensure the coating is applied evenly and within the recommended time frame for measurement.
- Measure WFT: Use a notched gauge to take measurements immediately after application.
- Record Data: Log the measurements and any relevant notes in the worksheet.
- Adjust Application: If necessary, modify application techniques to achieve the target WFT.
Important Terms Related to WFT Worksheet
Understanding key terms related to the WFT worksheet is essential for effective use:
- Wet Film Thickness (WFT): The thickness of the coating while it is still wet.
- Dry Film Thickness (DFT): The thickness of the coating after it has dried.
- Solids by Volume: The percentage of solid material in the coating compared to the total volume.
