Grain Filling with Shellac

[Harvey Pascoe]

However, it will (and I say this from modest experience) heat the surface most, which will cause premature drying of the top layer, which can impede the underlying finish from drying efficiently. This may cause subsequent coats to remain soft or the overall surface to remain soft.

Even shellac may appear to be dry, but should really be given good time to dry thru and thru. When I'm applying shellac, I only do several coats within the hour if they are very thin cuts. But if yr schedule works for you, power to you!

Yes I have heard many people say this and it is certainly true for any finish that relies on evaporation like shellac. But for chemical cures like varnish, it is less true. Obviously any fast build finish is going to result in a longer cure and may result in surface finish checking. I've made that mistake with varnish. As I mentioned, I did have trouble with shellac drying at 1:3 but by extending to 1:4 it went ok. You quickly get the message by how well it sands - if your paper clogs up, its not dry! Applying more than one coat of shellac without sanding between makes it even worse.

[Stewie Simpson]

Yes I have heard many people say this and it is certainly true for any finish that relies on evaporation like shellac. But for chemical cures like varnish, it is less true. Obviously any fast build finish is going to result in a longer cure and may result in surface finish checking. I've made that mistake with varnish. As I mentioned, I did have trouble with shellac drying at 1:3 but by extending to 1:4 it went ok. You quickly get the message by how well it sands - if your paper clogs up, its not dry! Applying more than one coat of shellac without sanding between makes it even worse.

I agree with Harvey. 1 coat between sandings is a much better practice. Treat the shellac as a grain filler and wet sand back to surface wood with 220 and 400.

[Harvey Pascoe]

Sheesh, this is amazing. At first I though I was the only one who stayed home for the holiday but then I noted that we got 749 people online to this forum and almost no posts! Just readers I guess. Nobody have any dumb questions?

[Jack Clark]

Nobody have any dumb questions?

Okay, I'll bite.

Stewie, what are you using for a lubricant when you wet sand shellac?

[Kent A Bathurst]

. Nobody have any dumb questions?

Not me, but I'm always happy to take the other side - ask an insightful question, and I'll give you a dumb answer.

[Prashun Patel]

"But for chemical cures like varnish, it is less true"

Some varnishes rely on oxygen to cure. Once a skin forms, it blocks the oxygen.

"[shellac]: You quickly get the message by how well it sands - if your paper clogs up, its not dry!"

Not trying to be difficult, but even if it sands ok, applying too many coats too quickly and then heating the surface can cause a shellacked surface to blister. It's happened to me.

[Stewie Simpson]

Okay, I'll bite.

Stewie, what are you using for a lubricant when you wet sand shellac?

Hi Jack. I find water is a good enough lubricant to use. I keep a bowl of it handy to keep strips of wet & dry paper soaking ready to use as required. Hope it helps.

Stewie.

[Harvey Pascoe]

In addition to pigmented fillers, you can buy transparent paste fillers - I think they are silica based. In any case, they do exist, and are an alternative to the shellac method.

I've been looking for that but haven't found anything but water based. Do you know of any brand names?

[Harvey Pascoe]

Not trying to be difficult, but even if it sands ok, applying too many coats too quickly and then heating the surface can cause a shellacked surface to blister. It's happened to me.

Sure will and I think I mentioned that earlier. Got to be careful about that. However, I got away with that today when I forgot and left the shellacked filled piece I just shot with varnish out in the sun for hours.

[Peter Clark]

Something I have had good results with is leaving the sanding dust (finish only) in the pours and using a thinner finish to remelt the sanding dust on subsequent coats. Seems to fill the pours faster....

[Harvey Pascoe]

Something I have had good results with is leaving the sanding dust (finish only) in the pours and using a thinner finish to remelt the sanding dust on subsequent coats. Seems to fill the pours faster....

I've done that and it seems to me it leaves it with sort of a muddy appearance and reduces the prismatic effect (chatoyance) of fine woods. Now that I've finished the India rosewood box grain filled with shellac, I'm not happy with it. Not nearly as nice as a built up varnish finish. The crispness of the wood grain is lost. Maybe that is because my shellac is too dark so I'll try it again later with ultra blonde.

Here is what truly fine varnish finish can look like. This is on teak a very grain porous wood with no fillers used, strictly a built up finish using Interlux High Build. You can imagine how many coats that was! That was one of the most perfect finishes I've ever seen, and on a vertical surface no less. I took that photo and it is every bit as good as it looks.

[Scott Holmes]

Harvey,

If your shellac looks muddy then you left sanding dust in the pores. I have found that the best way to fill with shellac (I use super blonde) is to apply 2 or 3 heavy coats a few hours apart. Then I let it dry for a day or two. Scrap or sand it back to the bare wood leaving the shellac in the pores only.

FYI - wet sanding between coats can leave sanding slurry in the pores that will NOT alwaysdisappear when the next coat of finish is applied. Wet sanding is for rubbing out finishes not for between coat flattening.

[Prashun Patel]

I've been doing some experimenting with wetsanding varnish in between coats. I've been using this technique lately, and a recent article in FWW by Michael Pekovitch(sp?) uses a wetstanding technique after the sealing coat is complete.

I've found that wetsanding finish with 400 or 600 grit sandpaper leaves no noticeable muddiness on walnut or cherry. Wetsanding at higher grits CAN leave swirls and streaks. I wouldn't call this muddiness, but it does appear that fine slurry is trapped and not easily removed. I'm guessing. You can mitigate this by buffing vigorously. All this applies to oil varnish and wiping varnish finishes.

[Harvey Pascoe]

Thanks for that, but no way would I wet sand. For one thing, I'm using thin wood that is a veneer laminate and it would warp. Could be that I didn't get all the dust out and I definitely din't get down to bare wood.I thought the shellac might give the wood a warmer glow; it didn't. My super blonde should arrive today and I'll run some tests with it and see how that goes.

I'm not saying the results were bad, its just that when I put the shellac-filled piece next to one that wasn't, there is a very noticeable difference apparent when both are seen in direct sunlight. In artificial light, it hardly shows. In theory, there should be no difference if the tone of the shellac is the same or less than that of the varnish.

[Scott Holmes]

I have a sample piece that I show in my finishing classes; the shellac filled side blows the filler side away as far as clarity is involved. Are you using de-waxed shellac? You should be using dewaxed as a filler.