Grain Filling with Shellac

[Harvey Pascoe]

I was using dewaxed orange shellac, or so they say, but I've no way of knowing if true. I just got my super blonde and now see why I had a problem: the blonde is very clear whereas the orange is opaque and muddy looking, even when freshly mixed. On a test piece the blonde produced no color change other than the normal wetting effect.

[Harvey Pascoe]

As a follow up to this thread, I just finished a box top of maple burl and African blackwood with four coats of super blonde and was surprised to see it turn out lighter than expected, lighter than if I had just layed down the varnish first. The nice thing was that with the shellac, the burl didn't absorb varnish like a sponge and I should be able to reduce the finish from 5-6 coats to three, so there is a big time savings here.

[Scott Holmes]

If your orange shellac was not optically clean then the wax has not been removed.

Shellac is an excellent sealer. Don't get carried away with the shellac; you can apply it thick to fill the grain, because you are sanding/scraping most of it away after it dries.

For a seal coat just 1 or 2 light coats; too thick and you will have problems down the road when the shellac wants to alligator (crack).

[Harvey Pascoe]

If your orange shellac was not optically clean then the wax has not been removed.

Shellac is an excellent sealer. Don't get carried away with the shellac; you can apply it thick to fill the grain, because you are sanding/scraping most of it away after it dries.

For a seal coat just 1 or 2 light coats; too thick and you will have problems down the road when the shellac wants to alligator (crack).

Oh, really? That's good advice because that is exactly what I was doing, using around 4 coats under varnish! When I see real old antiques and they have that alligatored finish, is that shellac? Just for grins I finished the insides of a box with rubbed out shellac. Very nice finish but is that going to be a problem later?

No, Scott the orange shellac was not optically clear after mixing. Very cloudy in fact. Thanks much.

[Scott Holmes]

Oh, really? That's good advice because that is exactly what I was doing, using around 4 coats under varnish! When I see real old antiques and they have that alligatored finish, is that shellac? Just for grins I finished the insides of a box with rubbed out shellac. Very nice finish but is that going to be a problem later?

No, Scott the orange shellac was not optically clear after mixing. Very cloudy in fact. Thanks much.

Harvey,

Old shellac that has an alligator look... First, a very thorough cleaning, then brush with denatured alcohol to get the shellac to reflow and level out. It will take several brushings. Padding is another option. There is no need for more shellac there is already too much.

Bonus: You are not removing the original finish...

[Harvey Pascoe]

Hmm, this raises an interesting question. Alligatoring or checking so far as I know is caused by what I know as "post cure", which is to say that the finish continues to cure over years and shrinks. very old varnish will do that even with only interior exposure. Could this be due to exposure to various environmental contaminates, or is the finish continuing to give off volatiles or what? I have a hard time with the thought that shellac continues to cure, so what would cause the checking?

Or could it be that the method of applying the finish of these production goods was designed for speed and not durability by laying on too many coats, too fast?

[Scott Holmes]

My opinion is that the shellac is too thick and will alligator over time. Shellac does not cure. It dries. Re-introduce the solvent (DN alcohol) it re-dissolves.

The prefect shellac finish: the thinnest possible film finish that is flawless.

[Howard Acheson]

>>>> Alligatoring or checking so far as I know is caused by what I know as "post cure", which is to say that the finish continues to cure over years and shrinks

One of the biggest reasons for shellac alligatoring is longtime seasonal expansion/contraction of the wood substrate. Shellac is a very inflexible material. When applied too thickly, it will alligator in a couple of years. The thicker the coat, the more likely it will alligator. When applied thinly, it can alligator with enough time.

[Peter Clark]

My opinion is that the shellac is too thick and will alligator over time. Shellac does not cure. It dries. Re-introduce the solvent (DN alcohol) it re-dissolves.

The prefect shellac finish: the thinnest possible film finish that is flawless.

Lacquer is very similar- To thick, It will crack because it doesn't move with the wood underneath the finish.

[Joel Wesseling]

The finish is ejected from the exposed cell and mounds up along the upper edges of the cell

Harvey and others, I need your help please.

I've been trying to figure out grain filling for some time now and it's been a challenge

Veneered Mahogany speaker cabinets: cant seem to fill the grain after about 10 coats of Target grain filler an another ten coats of super blonde shellac dissolved it Iso

Is the filler being ejected? Maybe

I'm using 1lb cut of shellac.. Maybe should be thicker?

Sanding after 3 or 4 coats

Just ordered 2 part epoxy filler that I will try on next cabinets. Noticed some Luthiers do it this way

Thanks, Joel

[Scott Holmes]

Joel,

10 coats of filler... How are you applying it?

When I fill with shellac I use a 2-3# cut and give it a coat or two then sand it back to bare wood leaving the shellac in the pores only.

1# cut is reallly thin it may be pulling the other coats out.

[Prashun Patel]

Also, how are you applying the grain filler? Are you letting it set up properly before buffing? For the shellac, since yr going to sand back, you can use a thick cut - 2-3# and you don't have to be so neat about it (except for the final coat).

[Harvey Pascoe]

Echo - ten coats? I recently did a test with quarter sawn ash and got complete fill with 6 coats mixed 1:4 by weight and I'm sure they were not completely dry between coats because I did this fast.

FYI, Epoxy is hideously toxic and you can develop a terrible allergy to the stuff, breaking out in terrible rashes that itch for weeks so bad it keeps you awake at night. After using the stuff for years, today I can't even get near epoxy. The dust will also wreck your sinuses. Sanding the stuff makes it that much worse when the fine dust goes all over you.

[Scott Holmes]

Harvey,

What system are you using for your shellac measurements?

I've see shellac measured in pounds of dry flakes per gallon or alcohol for many years. e.g. 1# cut, 2# cut, etc..

Ratios 1::4 or the like don't fit in that scope...

[Joel Wesseling]

I was wondering about the toxicity of epoxy filler. Really love shellac and want to figure it all out.. $50 for this epoxy too

I'm Padding it on in lines. builds up on surface with no problem

so I should weight the alcahol and shellac (ie)100grams of shellac to 400grams of alcaho. I'll see if this compares to a 3# cut.
I'll try this because I love shellac

I'll also hit you up later to about getting nice final coats by hand without spraying

Joel