Does Lacquer "Burn in" to Shellac?
Shellac and lacquer melt together when applied in layers. January 9, 2007
I have been refinishing the cabinets throughout a home (kitchen, baths, laundry, built-ins). Original finish was unknown, so I TSP washed the wood, lightly sanded, sprayed Zinn Sealcoat shellac (un-thinned). I will be spraying a Mohawk satin black lacquer as the topcoat. Does the lacquer burn into the shellac for bonding, or do I need to scuff sand the shellac sealer coat for a mechanical bond? The shellac went on well (maybe a little heavy). The bulk of the refinishing are the 92 doors/drawer fronts, raised panel with lots of profiles. Any shortcuts to ensure topcoat bonding?
From contributor V:
Just from my experience, I didn't have to sand the shellac, but I usually did just for a better and smoother finish. However, while yes, the lacquer will burn into the shellac, it can, if applied too thick, especially on the first coat, burn into it enough to react with the finish below. I can now put lacquer over poly with shellac in the middle, but the first time I tried it I got the second coat on real heavy and it curdled. Since then I do a couple of light coats to start and then it's good to go.
From contributor M:
Both the shellac and the NC coatings are evaporative coatings, which means they dissolve into one another. Regardless of how many coats you apply, you have one coat - there are no layers as in reactive coatings. Unless there are problems in the last coat of shellac, like drips, runs, overspray, dirt in the coating, etc, if the last coating is smooth, sanding is not needed, but it won't hurt one way or the other.
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