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Making shellac stick or filler

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Making shellac stick or filler

Postby Bob Howell » Fri Apr 21, 2017 3:30 pm

Most places are offering synthetic shellac sticks but they make no sense to me filling voids on a guitar. So I tried to evaporate the alcohol in Zinnzer Sealcoat. Turned creamy amber, so I'm not sure what I have . Some reaction but not sure I can use it. Letting it dry to see what happens.

Dabbing Sealcoat on voids never seems to fill them. I could get flakes and make a stick, but would rather just use what I have. Anyone worked this out?
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Re: Making shellac stick or filler

Postby Barry Daniels » Sat Apr 22, 2017 10:37 am

Shellac sticks are really intended for filling dings in finished furniture. Are you needing to repair places in a finished guitar or trying to get a new build ready for finish?

Trying to make your own filler sounds like a troublesome affair.
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Re: Making shellac stick or filler

Postby Bob Howell » Sat Apr 22, 2017 2:10 pm

Trying to get a new build ready for finish. G T, T suggest shellac sticks for filling voids'. Elsewhere I have seen hhg recommended.
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Re: Making shellac stick or filler

Postby Barry Daniels » Sat Apr 22, 2017 3:47 pm

A shellac stick works well on ebony and maybe a few other very dark woods but I wouldn't use it anywhere else. The problem with lighter colored woods is that you don't know what the color will be until a finish is applied which always darkens the wood to various degrees. The shellac stick fill does not darken under finish. So it is hard to know what color to use if you do this before finishing. It often shows up like a sore thumb.

I do everything I can to prevent voids so usually do not have to worry about defect fills. If a chunk of wood does go missing I will splice in some matching wood which always looks better than any filler or putty.

Glue or glue/sawdust fills suffer from the same problems a stick shellac so they are to be avoided too.

I deal with the tiny voids that usually show up around bindings and the rosette during the finishing stage by doing drop fills of lacquer.
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Re: Making shellac stick or filler

Postby Bob Howell » Sat Apr 22, 2017 9:52 pm

Compaino recommended shellac sticks of different color. I have never used them but going on his rec. On other types of projects I have used chips of wood and sawdust paste. I'm going to use a mixture of what I've done in the past as shellac stick does not seem to be common.
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Re: Making shellac stick or filler

Postby Bill Raymond » Sun Apr 23, 2017 2:10 am

Genuine shellac sticks are available from Constantines or from shellac.net, should you decide to use them. Probably easier to buy them than try to make them.
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Re: Making shellac stick or filler

Postby David King » Tue Apr 25, 2017 12:10 pm

The best shellac sticks I've ever come across were from Germany, they were round and about 5/8" in diameter with a paper wrapper in case anyone ever sees them. They had what seemed to be short fibers, possibly wool, embedded in them that made them much stronger and gave them a visible grain.

I have a set of the Constantines here that includes about 10 colors which is a good start as you can mix and match as you go but they certainly aren't made of shellac, they have a distinct styrene odor to them I'd say when you get them hot. They are also extremely brittle so you have to wrap them in something soft and contain them in a padded box. Constantines also sells a transparent amber stick which I don't own but it would be handy.
Getting the stuff to go where you want it and stay put without bubbling out is a trick and I use a variable, temperature controlled soldering station set at the lowest setting which is about 200ºC. You need to preheat the hole or gap first and then lay the shellac stick in there the best you can and smooth it out with a plastic spatula while it's still pliable (about 250ms). I've tried to mimic wood grain by drawing in a little layer of the dark brown or black stick over the lighter color. All i can say is that the more mistakes you make in your wood work the better you'll get at fixing them invisibly.

These might be the ones I used 30 years ago that i liked so much: http://www.apatina-restaurierungsbedarf ... ellack-110
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Re: Making shellac stick or filler

Postby Bryan Bear » Tue Apr 25, 2017 12:52 pm

I don't mean to derail this thread but have a related question about small fills (near bindings) for finish prep. The OP and I may be seeking the exact same solution.

I have a walnut guitar that I have set aside for a while to decide how to proceed. I had a stupid mishap with the rim but the particular back and side set has a certain sentimental value so I decided to press on. I was able to block sand most of the problem out but I don't want to go any thinner. Now I have a small area near the binding that is deeper (not by very much) than the rest and has CA in it from the binding operation. This is a guitar for me and I will press on no mater how bad this spot looks but I'd like to hide it as best as I can.

I was planning on pore filling with z-poxy (first time with that) and leaving a thin "grain popping" film over the whole surface. I was thinking about filling this area with z-poxy. Does this seem reasonable?
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Re: Making shellac stick or filler

Postby Barry Daniels » Tue Apr 25, 2017 3:02 pm

That should work fine because cured epoxy can be topped by more epoxy. Just sand or scrape the repair level before doing the pore filling. However, if the area is already filled with CA then there is nothing to be gained by digging that out and replacing it with epoxy. CA works as a depression filler very similarly to epoxy and they are compatible with each other and most finishes.
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Re: Making shellac stick or filler

Postby Bryan Bear » Tue Apr 25, 2017 3:39 pm

Thanks for confirming my gut feeling. the area is not "filled" with CA it just has water thin CA on the surface from gluing in the bindings. I suppose that may show up a little different under epoxy but probably not too badly.
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Re: Making shellac stick or filler

Postby David King » Wed Apr 26, 2017 12:59 am

Well CA cleans up very easily with acetone and rubbing along the grain using a paper towel folded up. It may take a couple of applications but it will all come off in a minute or two.
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Re: Making shellac stick or filler

Postby Bryan Bear » Wed Apr 26, 2017 10:31 am

Interesting, Thanks! I knew acetone broke CA down but never really thought of using it to remove it from wood grain.
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Re: Making shellac stick or filler

Postby Bob Howell » Wed May 10, 2017 4:24 pm

Well, I found out that after Sealcoat sits for 3-4 weeks it is still sticky and when dabbed into a void on scrap it remains sticky. Something bad going on but not worth pursuing. Another rabbit trail.

I got some blond flaks which will do the job.
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