Dealing with SHELLAC RUNS

[Alan Tolchinsky]

Hi All, I use Zinnser SealCoat after staining to seal the stain and reduce the number of wipe on poly coats afterwards. But when brushing as carefully as I can, I always get some runs and other undesirable surface defects. Even though I'm saving time with fewer coats of poly, the shellac coat seems to take too long to correct and smooth. Any suggestions as to what I'm doing wrong. I'm trying to apply as thin a coat as possible. Thanks in advance.

[Larry Fox]

If it is runs I would say that you are either putting it on too thick or you might want to try and reduce it to a thinner cut. Also, once you put it on, leave it alone - that is, don't go back over it and "tip" it like you would with an oil paint or slow-drying varnish. Might want to try padding it on also.

[Gary McKown]

I agree with Larry about reducing the cut. IIRC, Sealcoat is a 2 lb. cut - I always reduce it by half or more for sealing.

Mix up only what is needed, though. As Dresdner and others have pointed out, the greater the proportion of alcohol, the lesser the shelf life of shellac (even the stabilized brand).

[Warren Clemans]

I agree with the previous comments--try a thinner cut. That's one good reason to mix your own from flakes. It's cheaper, also, assuming you buy your flakes online rather than getting the overpriced stuff in the blue and white plastic jars.

Try loading your brush a little less. I get the best results when I just barely touch the tip of the brush to the surface of the shellac in the pot. It takes a little longer to get a good coat, but I get fewer lap marks and no runs. Treat it like you're brushing water, not paint.

Shellac has become pretty much my only finish over the last few years. Unless your project will take severe abuse, shellac with a final coat of good wax is the perfect coating. Skip the plastic stuff!

[Steve Schoene]

How are you applying the shellac? If by brush what kind of brush exactly? Runs are on vertical surfaces? What other kinds of surface defects?

[Brent Ring]

Thinner Cut - I have used a 1 lb and like its results.

[Steven Wilson]

Alan, I generally don't have problems with runs brushing a 3lb cut of shellac. IIRC I'm using Lilly Oval varnish brushes from Jeff Jewitt to apply shop shellac (W&N 580 in corners). Brush makes the difference, just flow on and let it dry. Having said that, I will get runs once and awhile and I get rid of them by using a single edge razor or using a card scraper. To level shellac with a card scraper just prepare it normally but don't turn a hook (so just square up the face). If you want to be aggressive turn a minimal hook. I can quickly level a shellac surface with a card scraper. After that it's pading time with shellac or go on with something else.

[Alan Tolchinsky]

Thanks all, I'm using a white bristle brush and trying to apply very thin coats. It's a 2 lb. cut and the can says to apply full strength for sealing. I'll try padding it on and see how it goes. Thanks a lot for all the help. I love shellac; I just wished it loved me.

[Warren Clemans]

There's an article on www.shellac.net that argues in favor of using synthetic brushes for shellac. You can't buy shellac at that site any more, but you can get free advice. Here's the guy's argument...it could be complete nonsense, but I use synthetic brushes and get good results.

"The logic behind the selection is this: to brush shellac properly you need to thin it down to a 1-2 pound cut, which is essentially water-like in its viscosity. In addition, since ethanol is one of the more polar solvents, water being the most polar solvent, it makes perfect sense to use brushes designed for water.

Finally, the highly cross-linked nylon bristle is virtually impervious to the physical or chemical effects of the acohol: no matter how many years you use one, nor how many hours a job takes, the performance of the bristle doesn't change, again if the brush is properly cared for.

The same cannot be said for natural bristle brushes, which as a bundle of protein chains do change their mechanical properties with repeated exposures to alcohol (they become less stiff and bouncy) while their chemical constitution remains relatively unchanged. This is in part do to the ability of proteins to absorb and adsorb polar solvents. Think of what happens to hide glue on exposure to polar solvents. In the case of water, it becomes gelatinized or liquid, the addition of alcohol unzips some of the polymeric structure. (Or even think about your own hair in the swimming pool)"

[Carl Eyman]

It is easy to get a run no matter how careful you are. At least it is for me. If and when I find one I can often shave it off very neatly with a cabinet scraper. The run being thicker than the surrounding finish seems to be softer and comes off very well. This procedure works best a few hours after the shellac has been on.

[Jason Scott]

When I have a run I just use a little alcohol on a pad to "blend" the run down into the finish, works great for me, I've never tried the card scraper technique, I would imagine you would need a really steady hand...

[Alan Tolchinsky]

Thanks again guys. I like the tips on dealing with the runs AFTER the fact. I used some 400 paper to sand some down but I usually seem to remove some stain in the process. Your suggestions sound better.

[Steven Wilson]

Alan, for sandpaper to work you need to let the shellac harden for a day or so. With a card scrapper (or razor blade) you can attack the run/drip after the shellac dries a bit (hour or so depending on temperature). You'll get a gummy mess if you hit hour old shellac with sandpaper. Sometime if you have an extra $20 purchase a very good brush - go see Jeff Jewitt he'll fix you up with the good stuff. I got setup 4 or 5 years ago and the brushes have been fantastic (for shellac or varnish) and are much better than Purdy brushes (which are good, just not optimal for shellac) I got from the Borg.

[Alan Tolchinsky]

Thanks Steve, Now that you mention it I don't think I let the shellac dry enough. It just seems to dry so fast you'd think you could work with it. But I'll wait longer as you suggest. Great tip!

[Steven Wilson]

Yeah the alcohol flashes off so quickly that you can easily recoat after a few minutes. It does need some time to harden up though if you want to work the finish. Applying shellac in cold weather has taught me to be patient and let it setup before I work it.