sanding an oil finish before top coating with lacquer
user-1117106498
| Posted in Finishing on
I used danish oil to pop cherry.
I waited a week to apply lacquer
But my question is : Do I sand the danish oil
finish before applying the lacquer?
Replies
As always there are number of ways to accomplish what you want to do. What works for me is a light sanding over the dried oil finish with 320 or red Sctochbrite pad by 3M.
I then apply a coat of SealCote (de-waxed shellac) by Zinzer. This is a barrier coat that allows most any top coat to adhere to the previous coat without problems. Seal Cote also controls the botching that is common in Cherry. You then can apply as many topcoats as you like.
A word of caution; do not build multiple coats of shellac if this piece will be exposed to UV as in a bay window. The shellac will get soft. Do your build coats with the lacquer.
Ask me how I know! I was doing an outdoor show with some of my pieces displayed on a table in the sun on a hot Georgetown, SC day.
A very detailed hand carved mahogany tea table, still in construction in which I had probably 5 coats of shellac on it became soft enough to show finger print impressions. I had to strip the whole table in all of the carved detail and start over. Hope this helps.
Danish Oil is a marketing term for a penetrating oil that contains some tung oil or linseed oil, some varnish and hardeners, as well as specific formulations for UV protection and other things. Each manufacturer has its own secret formula, which also determines the residual surface properties - the % of varnish, for example.
A Danish Oil finish, reasonably applied, should not require much sanding, but I do recommend a light sanding at 400 grit, preferably wet-sanded. Often, I'll take a very mild solution of Dawn and 400 grit to lightly 'sand' the fully-cured finish; then, a clean, clean wipe with water (the surface is waterproof at this point), then fully dry the surface.
Whether the lacquer will adhere to the Danish Oil is a question I can't answer... my guess is that it will
As a thought, the lacquer finish is probably softer than the Danish Oil/Varnish... other members will need to assess this.
Does the lacquer manufacturer have any guidance on surface prep? Some dont like to go over varnish, which DO has in it.
Putting a hard finish over a soft one, both with vastly different solvents is a long shot for me. I suspect the strong fast evaporating solvents will react with the varnish/oil and cause a mess. I once used laquer thinner instead of paint thinner to dilute spar varnish and the result was a disaster, it would puddle and never cured so I could not sand it away.
Personally I'd leave the Danish as the top finish.
You could scotchbrite the surface to get nibs out, or wet sand with very fine grade 400-600 sandpaper, then you're done. It works pretty well as a top finish.
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