Hi All
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I want to make up my own sanding sealer from Shellac.
Now after reading some of the posts around here I know some of you have a fascination and a deep erg to talk about Shellac so I thought I’d help out.
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I’ve just made up a cut of Blond de-waxed and I have some button that’s about 2 years old separated and hidden away at the back of a dark cupboard somewhere. I also have some Whiting which I was using as grain filler but it just made a mess.
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Any suggestions?
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Cheers
Replies
First of all, let's back up a bit and figure out what you mean by "sanding sealer." Commercial sanding sealer is designed to make sanding easy, by including lubricating stuff like zinc stearate. The downside is that the durability of the resulting finish is compromised.
So, with that in mind, what are you trying to do? If you just want a sealer (as opposed to a sanding sealer), then shellac is all you need (depending on your topcoat--some spray finishes work better with other kinds of sealers).
-Steve
I don't wish to hy-jack this thread, but it reminds me of a problem I had sanding some redwood, my ROS tended to leave the surface silky smooth but with pronounced valleys and hills along the grain lines.
A friend mentioned using sanding sealer to help "harden" the surface of the Redwood in order to achieve a flat surface.
Is this what you refer to as making sanding easier?
Cheers
John
John
Yes! I couldn't have put any better myself.
Most used woodworking terminology: Ooops.
Most useful tool: Wood burning stove.
Many softwoods have this problem--alternating bands of relatively hard and relatively soft wood. No matter what you do to the surface, you're going to have some residual amount of this, because the softer parts of the wood are resilient enough that even if you harden the surface, the wood below the surface is going to compress and then bounce back.
To deal with this problem, all you really need is a sealer (like shellac), not a sanding sealer. Any lightweight finish that penetrates into the surface fibers of the wood will do. Apart from shellac, you can use a thinned varnish, etc. Once you've applied it, you have to use a hard sanding block and a light touch. You may need to repeat the process two or three times to get a reasonably flat surface.
Substances that penetrate deeply into the wood, like low-viscosity cyanoacrylate glues (or maybe even Pentacryl), may work better, since they treat more of the wood than just the thin surface layer, but I haven't tried them. And cyanoacrylate will definitely affect the appearance of the finish.
Sanding sealers have additives that make it easier to get a smooth, flat surface, but at the expense of finish durability. I don't use them because of that--the benefits are outweighed by the drawbacks.
-Steve
John,
Your description smacks of familiarity to me.
A while back I chose pine to try my hand at carving and found that it left ridges, specifically with the harder winter part of the growth rings. The chisel seemed to ride over this part and drop down into the softer summer growth. I suppose if that was the look one were after then pine would be used as a traning material more often; but not really the look I wanted. :-)
I'd be curious to know if planing the surface with a really sharp blade and taking a very light cut, might prep the surface better than trying to do it with sealer. Once planed then proceed with whatever finishing schedule you want to use.
It would seem to me that the softer parts of the growth rings would soak up the sealer more than the hard parts thus balancing them out better.
Just me 2¢,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
A plane will provide a surface that has not followed the hard and soft grain as much as happens with sandpaper. But that advantage mostly disappears when you apply the first coat of finish. The finish penetrates more deeply into the softer more porous portions, but remains on the surface of the harder and denser portions. This actually accentuates the difference--what was a very smooth surface become rippled with the grain lines. But sanding off the high spots and repeating the sealing reduces the disparity as the soft parts become fully saturated. Eventually you can achieve the smooth surface you may be seeking, but it is more difficult than first it would seem.
Ahhh, light dawns on Marblehead.
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 6/11/2008 12:22 pm ET by KiddervilleAcres
"I'd be curious to know if planing the surface with a really sharp blade and taking a very light cut, might prep the surface better than trying to do it with sealer."
Even with the caveats that the other Steve mentioned, planing seems to do better than sanding overall. It works pretty well with southern yellow pine, which is notorious for the effect. But nothing will completely eliminate the problem, short of maybe something like those 1/4"-thick epoxy tabletop coatings.
-Steve
O.k
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So long to short what would be the best way/ procedure to get the surface as flat as possible on the item Attached.
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These boards have been planed had a going over with a card and sanded and as you can see the top looks like an off road track.
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That’s why I mentioned the Whiting to act as a bulking agent to help.
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There is something else I’m a little confused over.
I’m in the process of applying a wax finish to a box and I haven’t done this for a while so I thought I’d swat up and watch a video on FWW.
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Now Peter Gedrys applies a thin coat of shellac first and then proceeds to fill the pours with wax, well surly the shellac does that (it’s not like pours are the size of egg cups) and what would the shellac coat be referred to as just a sealer coat I presume?<!----><!---->
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All this come about because I read that you can use shellac to capture raised fibres and sand them down. Hence sanding sealer. I have a 2.5lb cut of blond made up IF I WERE to try this should the cut be thinned down?<!----><!---->
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Cheers<!----><!---->
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Glynn<!----><!---->
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Most used woodworking terminology: Ooops.
Most useful tool: Wood burning stove.
What is the finish that is already on the chest? Do you want to preserve that finish, or start from scratch? Do you want a glossy or satin finish in the end?
Wood with lots of knots is never going to remain perfectly flat, since the grain runs in all different directions, and the expansion/contraction rates vary with the grain direction. But you should be able to get reasonably close.
-Steve
Saschafer.
The topping on that cake is Blond Shellac which went to my parents but I now have 2 others. Plus I’m making one to keep which I shell also French polish (and if any purists have tuned in I DON’T CARE I need things to practise on).
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But before I do my own one I want to try and get a piano finish or as near as dam it on one of the others (minus the nail holes of course).
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The thing is even between the nail holes the lid is uneven.
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Cheers
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Glynn
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Most used woodworking terminology: Ooops.
Most useful tool: Wood burning stove.
I'd begin by sanding as smooth and flat as possible. With the wood you have, that means not using a random orbit sander, since it's going to ride over the hard parts and cut into the soft parts. A wide-bed panel sander would probably be ideal, but assuming you don't have access to something like that, I'd hand sand along the grain using a hard rubber sanding block. Depending on how flat the wood came out of the milling stage, the starting point would probably be around P100 or P120 grit.
I'd sand up to about P220, then apply shellac. I like to use a pad, but you can brush it if you thin it out a bit. For padding, I find a 2-lb cut to be just about right. I use Zinsser SealCoat, which is fine straight from the can. If you brush, you may want to thin it some with denatured alcohol. It's kind of tradeoff between getting a smooth, level finish and it taking forever to do the job.
My normal practice is to do three coats, about an hour apart, then let it dry overnight. (You don't have to wait that long, but I find it to be a convenient schedule.) After every three coats, sand lightly with a hard block and P320 paper, just to cut down any dust nibs and lightly smooth the surface. The idea is not to get it completely flat, but rather to just remove the high spots.
Repeat the three-coats-and-sand process as many times as it takes to reach a point where the surface is as smooth and flat as desired. You can then topcoat with another finish if appropriate, or wet sand a little more finely (400 or 600 grit wet-or-dry paper) and apply a paste wax.
As always, do test pieces first.
-Steve
Bob
I did end up hand planing (LV LA Block) and sanding to get the desired result, not to much effort and an OK result.
Steve, your dead right my surface was finished with 4oz fibreglass cloth and epoxy so uneven absorbtion wasn't a problem but a thinner finish would less forgiving.
Thanks for the replys.
John
Just about every top coat is its own best sealer. It's not like paint where primers, with relatively more binder and less pigment, aid adhesion. As Steve Schafer said, the commercial sanding sealer mostly is an expedient for production at the cost of a less durable finish. There are a few professional finishes that do require a specific sealer product to enhance moisture resistance or improve adhesion. But in those cases the manufacturer will be quite specific about the need.
Shellac is often used as a sealer because it is quick drying and does a good job of separating incompatible materials. Given what you have, fresh blonde shellac would work fine. Discard the buttonlac. If it was mixed two years ago it is over the hill and may dry slowly and soft, or not at all. I can't see any function for the whiting in this context.
Peter Gedrys has made a suggestion to make shellac sand more easily, and that is to add a small amount of sandarac resin to the shellac. Sandarac is alcohol soluble and quite light colored. You won't notice any difference in how the material is applied or how it looks.
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