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Thread: shellac problems

  1. #1
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    shellac problems

    well i am gonna show a problem i have ran into.. and its just that a run or two. i have never had trouble with shellac before but have this time. i sanded this to 150 grit by RO sander, then assembled, had glue squeeze out, cleaned that up with dry rag and a scraper after it was assembled. sanded by hand to 220 checked the glue squeeze areas with dna, no signs of WHITE, but when i started sprayun the hand mixed garnet shellac, i instantly got problem areas. this has been sanded in between coats lightly with 320 and more aggressive when i had trouble. the first pic shows a strange pattern where the rails meet the sides??? like it was repelling the finish back from that area,, like a glow or magnetic field saying stay away from this joint? then when you tip your gun to spray underneath a rail you find out the top has cracked since you last use and you get drops of shellac in your shelf area. of course this is after you have sprayed other areas and its had chance to dry out some already. ok so i will stop complaining and ask the question ,, to the finish gurus like dave hawksford and such here.. i have tried to smooth out the troubled areas when they were wet the next coat and got them better but still not good.. this now has 4 coats of shellac on it.. oh one more thing does shellac go bad in the flake stage? and if so what are the symptoms of bad shellac,, this was around a 2lb cut +or-... thanks for any help..also am looking at covering this up and could go with a stain or glaze to brown it up some maybe even a toner in laquer which is next after i get some answers..
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    If in Doubt, Build it Stout!
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  2. #2
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    If I had to guess Larry I would say that glue got rubbed into the grain but I'm no expert so will be interested in what others have to say.
    A Turn N Time
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  3. #3
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    Well, as I said in last night's PM:

    First, I'd try using a razor blade to take off the worst of the runs, then let the remainder dry for a day or two befor having at it with sandpaper or coarse (green) Scotchbrite.

    As for the spotting, or strange pattern - whatever... - it sounds like there might be some oil or wax - most likely wax - on the wood. Shellac will usually just blend with most oils. It might not dry hard, then, though.

    I'm thinking you might have to scrape it off, degrease it, then reapply. If you do that, then after degreasing, and before re-shellacking, scrub it with Scotchbrite and denatured alcohol.

    That's the best I can come up with. Good luck!
    Jim D.
    Adapt, Improvise, Overcome!

  4. #4
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    Quote Originally Posted by Jim DeLaney View Post
    Well, as I said in last night's PM:

    First, I'd try using a razor blade to take off the worst of the runs, then let the remainder dry for a day or two befor having at it with sandpaper or coarse (green) Scotchbrite.

    As for the spotting, or strange pattern - whatever... - it sounds like there might be some oil or wax - most likely wax - on the wood. Shellac will usually just blend with most oils. It might not dry hard, then, though.

    I'm thinking you might have to scrape it off, degrease it, then reapply. If you do that, then after degreasing, and before re-shellacking, scrub it with Scotchbrite and denatured alcohol.

    That's the best I can come up with. Good luck!
    Larry in the future when dealing with squeeze out keep a wet rag handy, wipe away all of the glue with the wet rag, just wiping it up with a dry rag doesn't take care of the glue that has gotten down into the wood fiibers. As for fixing, the only solution I know is to remove the wood with the glue on it either by sanding or scraping
    "There’s a lot of work being done today that doesn’t have any soul in it. The technique may be the utmost perfection, yet it is lifeless. It doesn’t have a soul. I hope my furniture has a soul to it." - Sam Maloof
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  5. #5
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    I agree with the others here. When I get a reaction to glue that I didn't quite get out I will use a scraper if I can or some sanding profiles. Lee Valley and others carry these but a scrap of wood shaped accordingly will do.

    One good thing about shellac is it is easy to fix boo-boo's. I have had occasion to slip on some rubber gloves and soak a couple rags in DNA and go at it like
    I am trying to remove all the shellac from an area, which I am but, there is always a bit of "sealer" left soaked it. Then I scrape or sand the area and rebuild, blending into the good area surrounding the repair.

    HTH.
    Any sufficiently advanced technology is indistinguishable from magic.
    - Arthur C. Clarke

  6. #6
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    As you all know, I do spinny things. This means that I don't use much glue.

    That said, I do use a LOT of shellac. I have a rule when it comes to glue and Shellac.

    "Finish the piece, then glue it together." I tape the tennons and other glue areas, then brush, rub or spray the finish on the projest. If I get some finish on parts where it's not needed, a light sanding takes care of the problem. Any squeeze out is wiped off with a damp rag.

    Since I don't do production work, I have no idea whether it will work for you.

    Bruce






    '
    Bruce Shiverdecker - Retired Starving Artist ( No longer a Part timer at Woodcraft, Peoria, Il.)

    "The great thing about turning is that all you have to do is remove what's not needed and you have something beautiful. Nature does the hard part!"

  7. #7
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    well as i wrote, i had scraped it after the assembly with a card scraper and sanded the whole thing.. as for wax jim i had no wax near it..the only time it was any wax was when i hand planed the surface and i had some paraffin on the sole of the plane..but i will take the ideas and see if i can get this fixed well enough to go out the door. i also wiped this down with alcohol before i sprayed it..to check for any glue trouble. must be i had special glue that can hide from the alcohol trick huh
    If in Doubt, Build it Stout!
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  8. #8
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    Hey Larry, 1st the shellac will not go bad in the flake form.

    I also see a bounce back of the spray in the the under arm 1st pic. That's where the spray will bounce off one peace and create a line on the a jointing piece. Spray the piss coats to 1st to get a feel for the spray. I find that each piece will take a spray different and until I get in the grove I take it slow.

    With glue problems and other things that will cause irregularities I like to wipe on the shellac 1st to get a bit so the spray will have something to bond with.

    One thing that will give you some changes in color tone when scraping with a razor blade is going through one layer of wood into the next. This next layer will sometime cause a slight change in color.

    Spraying shellac it is also ******best****** to spray piss coats on 1st ! 3-4 coats will do the trick. This will help with the bonding and keep the shellac from pooling on raw wood. Piss coats can be done to finish a piece and you can get a piece to look like it has been hand rubbed with a little 600 sand at the end and another few piss coats over it.

    The problem with shellac it take so darn long to dry, it performs terribly and it sticks. I like Lacquers LOL
    Last edited by Dave Hawksford; 07-30-2010 at 12:51 PM.
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  9. #9
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    I don't know much about shellac but I do know incredible joints when I see them. Nice, Larry
    Faith, Hope & Charity

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