Tools & Microfiber2 min read

Wet-to-Dry Film Calculations: When the Volume-Solids Formula Applies

Calculate predicted dry-film thickness from wet thickness and volume solids, with clear limits for wipe-on ceramic coating applications.

Updated · NANOLAB Knowledge

For an appropriate conventional coating system, predicted dry-film thickness equals wet-film thickness multiplied by the volume-solids fraction. The calculation is useful only when the wet thickness and solids value genuinely describe the film being assessed.

Work through the units

An illustrative wet film of 80 micrometres at 60 percent volume solids predicts 48 micrometres dry: 80 × 0.60 = 48. To target 48 micrometres with the same assumptions, divide 48 by 0.60 to obtain 80 micrometres wet.

The percentage must be entered as a fraction. Using 60 instead of 0.60 creates a hundredfold error. Keep micrometres and mils in separate labelled columns if both appear in the project documents.

Identify where the model breaks down

A calculation based on liquid dispensed from a bottle is not the same as a wet-film measurement. Wipe-on detailing products lose material to applicators and levelling towels. Surface geometry, uneven distribution and reactive curing can add further uncertainty. A predicted value is not a laboratory measurement of the installed film.

Wet-film combs are also intended for suitable measurable wet films. Their scale and contact method may be inappropriate for a very thin detailing coating, and using one on a customer surface can disturb the application. Select a measurement method with the coating and instrument suppliers before testing.

Report the result honestly

Write the measured wet thickness, volume-solids source, calculation and assumptions together. Label the output as predicted thickness. If the contract needs a verified cured thickness, specify the validated measurement method and uncertainty separately.

For a NANOLAB installation, follow the product's documented application rate and levelling procedure. Do not increase the applied quantity merely to satisfy a calculation borrowed from industrial paint. Extra liquid can create a finishing problem without demonstrating additional useful protection.

Related guidance

Technical references: Elcometer: Calculating Dry Film Thickness.

For product-specific application instructions, consult NANOLAB technical documentation or ask about your surface and intended use.

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