Wet film, dry film and volume solids: compare what remains on a cabinet surface

When two cabinet finishing proposals quote the same number of coats, that does not establish the same amount of dry coating. The liquid film applied in the shop and the film remaining after drying are different quantities. Identify the coating system and whether a quoted thickness is wet or dry before comparing them. A thicker figure can describe a different basis rather than a more substantial finished surface.

Follow the quantity through the drying step

Elcometer explains the theoretical relationship as dry-film thickness equal to wet-film thickness multiplied by the volume-solids fraction. Its wet-film-comb guidance also describes a reading bracket between wet and dry teeth. The calculation is an estimate; the comb observes the wet layer.

Reading note: Elcometer: How to measure wet film thickness using wet film combs.

Volume solids is the proportion relevant to that volume relationship. Do not insert a solids-by-weight percentage just because it appears nearby on a data sheet. A value expressed by mass answers a different question. Similarly, the amount of liquid purchased is not a measurement of film remaining on a door. Product left in equipment or lost during application has not become part of the finished cabinet.

Keep the system boundary clear. A primer layer and a topcoat can serve different functions, so their thicknesses should not be collapsed into a boast about the thickest paint. A quotation may include a preparation coat that another system does not need. Compare the specified complete system, the intended finished result and the way conformity is checked. A single coat count cannot describe all of those decisions.

Compare coatings at the same required dry-film thickness

Suppose two hypothetical coatings are applied at 100 micrometers wet. Coating A has 40% volume solids, so the theoretical dry film is 100 × 0.40 = 40 micrometers. Coating B has 60% volume solids, giving 100 × 0.60 = 60 micrometers. If the comparison requires a hypothetical 40-micrometer dry basis, A corresponds to 40 ÷ 0.40 = 100 micrometers wet, while B corresponds to 40 ÷ 0.60 = approximately 66.7 micrometers wet. The buyer asks for both estimates on that same dry-film basis before comparing material quantities. These numbers are not instructions to apply either product at those thicknesses; an actual coating must permit the intended film build.

In that hypothetical comparison, the larger dry result from equal wet application does not establish that B is better. Adhesion, appearance, compatibility and performance under the intended use remain separate. The buyer accepts the corrected comparison basis and rejects the claim that equal wet readings prove equivalent finished coating. Selection between the actual systems then follows their documented suitability, approved finish sample and complete quoted scope, rather than a shortcut based on the larger solids percentage.

Separate a process reading from final acceptance

A wet-film reading can give the applicator feedback while work is underway. It does not prove that every location has the same film or that the eventual finished film meets the full specification. Keep the measurement location, method and process stage with the result. Do not record an estimated dry thickness as though an instrument directly measured the cured surface.

Profiled doors make the location especially important. A convenient flat test area may not describe a recess, sharp transition or edge. Decide how the finishing process is evaluated for the actual component instead of extrapolating a single easy reading over its entire shape. The selected coating instructions and the agreed inspection method should govern those locations; a generic numerical example cannot replace them.

Also distinguish theoretical film quantity from a purchase quantity. Real consumption includes the shop’s application process and losses. A procurement comparison can show the theoretical basis and the stated allowance separately, making an assumption visible rather than hiding it in an unexplained coverage claim. Changing the application method or part mix can change that allowance even if the finish code stays the same.

A useful finish submittal therefore identifies the system, the wet or dry basis, the product’s relevant data and how the completed surface will be assessed. It does not need to turn the homeowner into a coating inspector. It needs to keep similar-looking numbers from concealing different work, and to ensure the quoted finish is judged against its own intended construction.