Help: Shellac on Cherry

I'm in the process of building a Chery keepsake box. I've gotten all the parts cut and sanded, and have started to apply Zinnser Seal Coat which is a 2 lb cut of dewaxed shellac to all the insides of the box.

I've brushed on 2 coats (I don't own a srayer - yet!) and used 0000 steel wool in between coats, but notice that I have a couple of "ridges" in the shellac which I think I need to sand out before proceeding with a top coat.

I tried to use 300 grit wet/dry paper, but that didn't work out very well as the paper quickly loaded up with the shellac dust.

So a couple of quick questions:

1) Do I need to sand out these ridges or will subsequent applications "melt" the shellac below enough so it won't be noticeable.

2) If I do need to sand in between coats, can I use some sort of lubricant to keep my sandpaper from clogging up?

3) What do you recomeend for a topcoat over the shellac, if anything?

Thanks in advance for the help!!

Mat

New to finishing myself, so I can only comment on the clogging. Have you tried Norton 3X sandpapers? They claim they don't clog, and I found that to be true, at least with wipe on poly. They are a yellowish color, and are available at the borgs.

Dan

I've used shellac on cherry before with pretty good results. Without being able to see how thick of a ridge you're talking about, I think you'll have to remove it. Shellac is pretty good at melting out imperfections on previous coats to a degree. If your sanding and steel wool weren't enough to remove it already I'm guessing it might be too thick for another coat to disolve it out. Since it dries so quickly, it's pretty easy to smooth out and apply 2 more coats to the problem area before top-coating. The disolving effect should blend it right in with the surrounding area so that it doesn't look repaired. Sanding should work OK. My personal modus operandi would probably have me grabbing a small card scraper or a really sharp chisel to shave the ridged area smooth then maybe a real light sanding if there were any scraper marks.
As far as the paper clogging - are you using the stearated stuff (pale gray color) or just the normal dark gray (almost black) wet/dry? The stearated papers are better at resisting clogging, but the Borgs don't usually have them. You'll probably have to check woodworking or paint/finish stores or mail order.

Sounds like the ridge it too high to be "melted" by the next layer(s) of finish.

IME sanding the hump will probably result in a smaller hump, but will also reduce the surrounding layers of finish before the hump is small enough...even with the use of a flat sanding block.

Use a sharp card scraper (or chisel as Doug suggested) to knock down the hump to the previous layer. Lighter feather sand this area. Fill with a bit of shellac, then proceed to the next complete layer of finish. It should blend right in.

Two other things:
You might consider thinning the shellac to a 1# cut.
220 will work just fine if you don't apply too much pressure; or you can check automotive supply stores for finer wet/dry papers.

As for a top coat, once the shellac has completely hardened, load some 0000 steel wool with wax and buff the entire piece. This will impart a soft luster to shellac that has to be felt to be believed. It will simply glow.

When using shellac as a finish I don't sand in between coats. I will however remove runs and sags, usually with single edge razor blade. Before the last coat I will level sand the finish with 3M Freecut Gold sandpaper. I find the 3M paper doesn't load up easily. You can also use any sterated paper for level sanding, I wouldn't use wet/dry sandpaper though. As far as a topcoat for shellac I rarely, if ever use one. I make up fresh shellac and find that once it cures it's fairly impervious to most things (even spilt alcoholic drinks), besides it's real easy to repair shellac if needed. If you've used dewaxed shellac then you can top coat it with lacquer (regular or water born), varnish, or poly. If you decide on a top coat then you probably don't want too much shellac buildup, just enough to get the color your looking for. As for applying shellac with a brush, you should follow the technique described by Jeff Jewitt - you really want to flow the shellac on with a great brush. It's not the easiest technique to master, very different that applying paint or many other finishes. I use a brush to get the initial shellac build up, then I aggressively level sand. I pad on my final coats with rag, or a very fine artists brush (Windsor & Newton from Jeff Jewitt) for cutting into corners. Oops, almost forgot. Another trick for level sanding shellac is to use a well prepared card scraper that hasn't had a hook turned on it (or a very tiny hook); fast, accurate, and it doesn't load up.

To best use shellac, you have to unlearn your varnishing skills. Ideally, you want one coat of shellac (if brushing) and the thickness of the finish is controlled by the "cut" of the material. Some folks will apply several coats, but sand back (carefully) until the grain is filled...and then do one final coat. Others do multiple coats by padding techniques. It's very difficult to apply shellac with a brush and not get those darker ridges, although someone very skilled and using the right kind of brush can do pretty well.

That said, I will admit to doing multiple brushed coats by applying them quickly and with about a 1-lb cut. But only on flat surfaces where I was able to have more control of the situation. I still had some of the "Ridges" on edges, but after rubbing them down, I just wiped on some more finish with a soft lint-free towel to "finish" the finish in that area.

Great comments everyone, very helpful!

A couple of feedback points:

1) the sandpaper I am using is just plain wet/dry paper from the borg, so I'll have to pick up some of the stearated paper from Rockler next time I'm there.

2) I do have a nice thin card scraper, which I know how to use well, but I never even thought of using it in this situation. Duh!!! I'll give that a try.

3) Thanks for the suggestion about thinning it down to 1lb, I was thinking about trying that anyway as it drys so darn quick that I almost don't have enough time to get it laid down evenly on the entire piece before I lose the wet edge and the ridge starts to form.

4) Since I really don't expect the box to get a lot of heavy use, I'll forego the topcoat and use Dans advice about finishing with paste wax rubbed in with steel wool. I've done paste wax on top of shellac before and been very pleased with it, but I haven't used steel wool to apply it with.

5) Thanks for the advice on how to flow the shellac onto the surface the varnishing technique, I've definitely noticed that it behaves differently than varnish!

Well, back down to the shop I go to get rid of those ridges. I'll post pictures when the box is done.

Hi Mathew...I like using Sealcoat very much. It works great as a sealer or finish coat....the way I use it is to simply wipe it on using a blue shop towel(disposable kind) and then wipe it off immediatly...let it dry(takes maybe 20-30min. depending on temp and humidity) and then apply subsequent coats using another blue paper towel folded into a rectangle about 3"x6" dip it in the can, and then wipe, keeping a wet edge, in one direction only....if the area you are working in is warm, the shellac should level it's self out and no ridges will appear....if you have a thick ridge to contend with you can simply wipe along the length with a shop towel dipped in denatured alcohol (shellac's solvent) until it 's gone ....since shellac melts into itself you can easily reapply using the same wiping method....if you want to wet sand I think you can use naptha as the lubricant(I think)....I do the paste wax thing too afterwards....try it out; it just takes doing it a few times to get good results.

good luck,
Greg