Clear Topcoats over Tinted Pre-Catalyzed Lacquer
Finishers discuss the risk of "wet-line" defects when applying and sanding a clear topcoat over a tinted pre-cat base coat. May 11, 2006
Does anyone ever topcoat their painted pieces with a clear coat (in my case, Opticlear over Optiset)? Are there advantages or disadvantages to this process? If you are rubbing out a finish that is one coat pre-cat paint and two coats pre-cat clear, would there be any distinction if you rubbed through the two clear coats, or is the melting together of the coats enough to prevent any distinction? Is there any risk of there being anything similar to the halo effect experienced when rubbing through the layers of CV?
From contributor C:
Some clears will melt together (NC lacquer); some will not (most catalyzed products). Some will show distinct witness lines where other materials will show none or very subtle ones. On finishes that will be rubbed out thoroughly, it is best to test samples. Mostly I try to have a very smooth surface before the final coat and then spray a nice smooth, thick coat that will be rubbed quite smooth without any rub-throughs. One disadvantage that you should be aware of is that the clear coats are rarely totally clear... they often yellow, cloud or otherwise tint or obscure the paint colors (there are instances where this can be a useful effect too). One advantage is that the sheens are often easier to control and damage (scratches, etc.) often shows less on the clears than it would on the pigmented coats. I like to use some subtle spatter coats and they are best protected by topcoating (same is true of glazes).
From contributor M:
There are some finishes where the base color is achieved without any buildup of coating. In these cases, they will use clear coats to complete the finish. If the base colors are different whites or other light colors, then water clear coatings are used to complete the finish. If you're going to rub or polish your coatings, you should add a couple extra coats depending on the coating you will be using.
From contributor D:
You can also catalyze the Opticlear 3% to make the coating harder for rubbing out. You can also put the coats wet on wet to ensure the melting together of the two coats.
From Paul Snyder, forum technical advisor:
Instead of using Opticlear over paint (Optiset), I use ChemCab. It's a water-clear, non-yellowing finish from Chemcraft. Opticlear changes the color of the pigmented finish too much.
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