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Thread: Spray shellac first coat

  1. #1
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    I'm nearing completion on my #1. Things are looking good. I've opted for alchol dyes and a french polish finish. I've been working a bit with practice pieces and one thing I've noticed is that after I rub and spray on my sunburst, the first application of shellac rubs out a bit of the stain (both alcohol based). After that initial layer is down, things are fine as the stain is sealed in. However, especially on the spruce (pine for my practice bits) this leaves noticable blotchiness and streaking that isn't there after the staining is complete.

    Is there any reason that I shouldn't thin down my shellac and spray the initial coat directly on the instrument to accomplish this sealing? Will this somehow hinder the ultimate adhesion of the finish to the wood? Thanks in advance for your thoughts.

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    Registered User buddyellis's Avatar
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    Dudenbostel does it.

    I've done it on the last 2 instruments I made and it almost eliminated the 'smearing' issue. I used Bullseye can shellac, but putting a thinned down cut in your spray gun (along with a leveling agent/retarder) shouldn't be a problem and will probably allow you to get a thinner/more uniform coat than brushed.

    -b

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    Registered User sunburst's Avatar
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    I do it all the time.
    Be sure to spray a very light coat. The thinned shellac will run "like a freight train" if you spray too heavy, taking your stain with it leaving dark sag lines.

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    The only theoretical down side to it would be that in the French polish technique, you are really forcing the shellac into the wood and therefore the adhesion may be better with the padded on shellac. However as you're doing this over the dyed wood, it would tend to smear the colors.

    I sometimes spray a thin coat of shellac inside my acoustic guitars, doing the backs and sides. Works fine if not overdone.

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    I spray a thin coat of shellac after staining also. It seals the color and provides protection for the color while I scrape the binding.
    I then varnish, level and then french polish, it seems to me it would take a long time to build up to a final thickness using just french polish.

    Dave
    "Wait a minute.......Do that again".....

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    I sometimes use vinyl sealer. A light coat. Then as far as I've found you can do as you please over it. Out of curiousity, who sunburst dyes the wood (whatever way), seals with shellac, scrapes the binding, and then continues with shellac, french polish, with no barrier coat in between and doesn't expect color bleeding problems? Must be some very light fast drying undercoats if applied by hand. I believe even Gibson used varnish over the dye before FP. ??

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    Masamando Steve Hinde's Avatar
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    I do this on most everything stained. I use vinyl sealer on bare wood with lacquer. Be careful with the spray can shellac. It can give you some LARGE drops that will leave a spot in the color. Very light coats!! Even the layers after can cut through down to the color layer if you are not careful. Alcohol soluable materials will re-dissolve easily. Why not some color in the shellac if you spray with a gun? Could add a little depth to the appearance too.

    Steve

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    One approach to this "problem" is to use water based dyes. They are supposed to be more light fast than the solvent based ones, and the alcohol won't dissolve them near as much as the solvent based dyes.

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    Adrian Minarovic
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    But with water based stains the grain may rise if the wood wasn't prepared properly.
    If the wood is stained just on the very surface (e.g. airbrushed alcohol based stain that dries right on the top of the fibers) you can get the "washed" spots, but is the stain is applied by hand, the color is deep in the wood and the spots are less likely.
    I use airbrush for applying shellac and it works great both on sprayed and rubbed stain.
    Adrian

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    Registered User buddyellis's Avatar
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    I use hand rubbed water based dyes AND spray shellac as a base, but I also sand to 220 grit, then raise/wack the grain with 320 grit about 4 times.

    Most say 320 is overkill, but I find that it helps, especially on the spruce, to get more even staining. I always worried that alcohol based stains would smear easily/easier than water based. Heck with water based dyes you can almost wipe your binding down with acetone instead of scraping and get away with it (almost, but not quite)

    I also use a bit of colored shellac brushed with a small, flat, artists brush to darken/even out the vignette, the points, etc.




  11. #11

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    This will sound completely counter-intuitive, but I like to seal color with McFaddens lacquer no matter what I'm going to use for the final coats.
    Shellac will much more likely cause bleed unless you really get that thin coat on. Heavy laquer will bleed it too, but sets up so much more quickly it's usually not a problem. THEN I use a shellac coat if I'm going the varnish direction because it's so compatable with any finish medium.
    Dale, the vinyl sealer is actually much the same I think, lacquer with vinyl mixed in.

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    I have been useing hide glue to seal in the stain.It's been used for centuries on fiddles and it works great.It leaves the grain on the spruce more sparkly and seals better than anything.It's easy to apply,peels off the binding with a fingernail, and you end up putting on a lot less varnish to do the sealing. With each coat of varnish the previous coats will solve a little and they settle together as one coat making a long process of filling. Hide glue does it in one coat and isn't solved by the next varnish coats. Try it outand report back here. I'd like to hear others experiences.I first did it on a blonde mando because I was afraid of haveing two different woods with two different absorbtion rates. The hide glue made the different woods work like one wood because of the common sealer. It works great.
    Gary

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    Jim, you may be right. I should look on the can! But it smells like lacquer. I also use McFaddens as a sealer, and like you, if I'm going to varnish I use shellac over the lacquer because everything seems to bond well with it.

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    Formerly F5JOURNL Darryl Wolfe's Avatar
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    Quote Originally Posted by (testore @ Oct. 11 2006, 14:06)
    I have been useing hide glue to seal in the stain.It's been used for centuries
    I LIKE THAT IDEA. Will have to try that out next time. And now that you mention it, that may be what's under the varnish on my Loar. It is certainly a thin layer of something hard and shiny.
    Darryl G. Wolfe, The F5 Journal
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  15. #15

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    Gary,
    Do I understand correctlt that you are putting hide glue on after staining? I have heard of doing that before staining but not after. Does the cut matter much? Would you mind explaining your process a little more?

    Andrew

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    But if you use hide glue, wouldn't the instrument smell like hooves and snouts?

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    I stain it like usual, then apply a thinish coat of freshly made hide glue with a hogs hair brush.The staining process kinda burnishes the wood and the grain doesn't raise all that much. It has worked real nicely on my last several mandos. Also I think there is something acoustical happening too. My stuff has a more clear sound,maybe brighter. Not sure. Like I said it's been used in the fiddle world for about 400 years. I'll try to include a tight pic of my latest top to get some feedback. I think the effects are good, visually and acoustically.
    Gary



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    Jim,
    I make mine smell like Jello,strawberry is my favorite!

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    Registered User sunburst's Avatar
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    I like the smell of lac bug excrement...

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    Adrian Minarovic
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    Darryl, you can test if it is hide glue by touching it with moist finger. If it's hide glue it would feel sticky and would wear off rather easily. And hide glue wouldn't be as shiny, IMO.
    Adrian

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    Shiny ?. Do you mean under varnish?I think hide glue under varnish looks like it sparkles some. Also, old hide glue can take forever to solve and get tacky.I'm including a pic I took at Loar fest that got me thinking. This looks like a hide glue sealer to me. The way the varnish darkens and the way it has peeled off the wood reminds me a great deal of very old German violin work I've seen a million times. The Germans almost always sealed with hide glue.
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    Formerly F5JOURNL Darryl Wolfe's Avatar
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    Quote Originally Posted by (testore @ Oct. 12 2006, 11:17)
    Shiny ?. Do you mean under varnish?
    I do not think any of it shows now, but will check to see for photo op. When I got the mando, perspiration had deteriorated the varnish on the back in the armpit area. Maybe 3/4" x 3" at the edge. There was a thin, hard, shiny coat of something directly under the varnish. That coat was not affected. The varnish went from perfect to soft and sticky as you approached the affected area and then to non-existant revealing that undercoat. I simply french polished it and you cannot tell anymore.

    All I can with any certainty is that there are two different material on it. Something over the stain and then varnish
    Darryl G. Wolfe, The F5 Journal
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    Darryl, it got sticky? that's interesting. Thanks

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    Maybe it was from the armpit.

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    http://www.milburnguitars.com/fpbannerframes.html

    I found this site very informative for varnish technique. Their current preference is to use epoxy over the entire instrument. Hide glue sounds more traditional!
    david blair

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