Finishing blanket chest. Outside sanded through 0000 steel wool and then tung oil.(4 coats thinned to
4-1) Inside using amber shellac because I'm not crazy about oils in contact with clothing. Question is.....how far do I go so that shellac will bond well. 150? 180? 220? Planning on 3 coats. sanded between coats.IME, 150 is plenty far enough ... 180 for the anal.
IME, sand/steel wool, lightly, only after the first coat unless there is an obvious need to between coats.
Then wait 30 days and rub down with a brown paper bag.
YMMV ...
A very fine "abrasive" ... there are "film" type abrasives that work equally as well, but a brown paper bag is a whole lot cheaper. I use the paper from a grocery bag to rub down the final coat on all the shellacked pieces I spray.
Seems to me that if there are any undried oil to be in contact with clothing then you don't have any chance of getting shellac to bond to it. Am I misunderstanding something here?
Bond well? Shellac is and evaporative finish. This means that when you apply one coat of evaporative finish on top of another, the solvent of the new coat partially dissolves the previous coat, and thus forms a bond between coats.
Shellac will bond with oil. It's often used to connect dissimilar finishes, including oils.
Sorry if I wasn't clear. The shellac will be put on the raw wood
Generally the first coat of shellac is going to penetrate into the wood, depending on the shellac "cut" (dilution). The solvent is alcohol and that will soak into most woods enough to establish a "bond" at relatively high grit numbers.
What kind of wood is the inside (closed pore or open pore)? Do you want a very smooth glossy finish?
The higher the last grit of sandpaper, the smoother the wood and the harder it is for a liquid to penetrate. For the inside of a chest, I think I'd stop at 180, again, depending on the type of wood and how smooth you want the finish.
And by the way, the best thing to do is try the finish on some scraps first. No sense guessing when dealing with a finish.
Why would it be more difficult for the finish to penetrate at higher grits? The pores are still going to be there at the same density and the same pore diameter.?. The only thing that has changed is that the scratches left by the lower grits are finer. Why would 'finer' scratches produces less penetration of an alcohol soluble finish? Unless I am mistaken, most of the finish is going to penetrate into pores, not scratches.
Do a test, but I wouldn't worry. Shellac will stick to oily wood better than anything else except oil. I've never had it not stick when French polishing with a mineral oil - pumice prep. The shellac sinks under the oil, displacing it to be wiped off with naptha as the final step.
I misunderstood the OP; he wants to put the oil and shellac in different places. Sorry.
Extremely high grits are more prone to burnishing the wood, which will harden and tighten the fibers to the point where a high viscosity finish has a difficult time penetrating.
Shellac works like water, because of its polar solvent, so it's the equivalent of that water wipe you use to set up those fibers and break the case-hardening. Sand until you're happy, apply the first coat of shellac, and you'll still have to dewhisker a bit.
Either way, Shellac will still bond with an oil finish. I know he's planning to do the two seperately, but shellac is often used to provide a bond between two dissimilar finishes. Just fyi.
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