Shellac finish on padauk & movingui

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  • #332197
    dreman
    Participant

    Hi,

    I’m going to make a chessboard. I’m planning to use padauk & movingui.

    The problem is that both species contain natural pigments. And there’s a high risk that I will spoil the chessboard if I try to apply shellac in the traditional way (i.e. with a brush or a piece of cloth.)

    So, the question is: how to apply shellac finish onto a padauk & movingui chessboard?

    #332276
    David B
    Participant

    Good question b/c you’re right–it can bleed quite a bit. Perhaps the simple answer is “very carefully”?

    #332365
    Ed
    Participant

    Would spraying solve the problem? A chess board isn’t very large, so it isn’t crazy to buy canned, aerosol spray shellac. I must say, I’ve not been happy with the blurpy spray quality from Zinnser’s spray shellac, but that may not matter here because the approach would be to spray the lightest possible first coats. You do *not* want a wet coat because you want zero chance of a run and don’t want to form a wet surface in which dyes/dust can migrate. You just want the barest, dry coat to lock things down. It will look dusty and incomplete. Let it dry, then put down another dry coat. Things will look awful at this point. Look at glazing light and watch for when you the few dry coats have covered everything and given you a complete barrier over the wood, even if bumpy from the dry spray and blurpy nozzle. There will probably be raised grain. Ignore it. Once you get to this point, you can spray a wetter coat. Again, it won’t look great, but you’ll have enough finish on after that first sort-of-wet coat that you can make a single wipe with 600 grit abrasive (foam backed like rhynosoft is my favorite) to knock off most of the fuzz. You’re not sanding…you’re wiping. It’s like painting with the abrasive, doing the airplane landing/takeoff thing. Take one pass down a strip, move over the width of your pass, and repeat. You may have fuzz left after, which is fine. Okay, at this point you’ve locked down the surface of the work under a barrier coat without dragging a brush. My hope is that you can then switch to a brush to build your real finish coats. Take care because shellac dissolves earlier coats and you don’t want to liberate those bottom layers. A light scuff between coats will kill the rest of the fuzz.

    So, that’s a guess at what I’d try. Glue up some scrap and see if it works. Scraping / planing rather than sanding may be important.

    This same general idea might also work with spray lacquer, like Deft. I don’t see why lacquer couldn’t be sprayed as the dry barrier coats and then you switch to shellac on top. I’m a little nervous that the lacquer thinner in the spray may cause bleeding, but you’ll know that by testing on scrap. The good thing, though, is that shellac (alcohol) will not dissolve lacquer. So, if you get the lacquer barrier coat on successfully, you can build shellac on top without as much fear of melting through.

    If you spray lacquer (from a can, or from anything), wear a half or full-face cartridge respirator (not dust mask) listed as suitable and educate yourself about fire/explosion risk. This is really true for the spray shellac, too, but the MEK in the lacquer needs to be taken very seriously in my opinion even spraying outdoors.

    #332405
    dreman
    Participant

    Thank you for the detailed answer.

    I’ll try to mix shellac with thinner and use an airbrush (which I have) for spraying. (As you suggest: dry coat and then wetter one)

    #332633
    dreman
    Participant

    Ed, spraying works.

    I thinned shellac and sprayed it onto a piece of padauk with an airbrush. The 1dt coat was pretty dry. When I applied the second one, I ensured all surface is well covered. Those two coats dried and I was able to sand them with steel wool slightly. No smudging.

    I think, I will be able to continue with a brush after those two coats dry.

    Thank you!

    #332767
    Ed
    Participant

    @dreman excellent! On the real piece, where more cutting, scraping, sanding, and handling has occurred, there could be different results, so when you get to the real chess board, you can always do the underside first as a test, just in case.

    I have an hvlp turbine, not an airbrush, and have never used an airbrush. On a small project like a chessboard, could you do all of your finish coats with the airbrush, or is the fan not the right shape? Or, maybe you need to thin too much to get decent build without going through a gallon of alcohol? Just curious.

    #332785
    dreman
    Participant

    @ed My airbrush (JAS 1120) was bought for a small projects like a chessboard (boxes or anything else of that size). So, I can use it for all painting I need for such projects. A full-size spray gun is overkill for me.

    I do not have to add too much thinner – I mixed almost even parts of thinner and shellac. (Actually, I had such mix ready, because I use it for my woodturning projects, and thinned shellac works much better for that. I followed Mike Waldt’s suggestion – you can see many his videos on youtube.)

    #332900
    SharpPencil
    Participant

    Would some body please tell me what is Paul’s current tuition …I keep asking without a reply

    #332944
    Ed
    Participant

    @cornflowers I’m not sure what you are asking. WWMC is $15 USD/month. See https://woodworkingmasterclasses.com/membership-signup/ . If you mean his in person classes, he won’t be teaching in 2018. Current class prices are at https://woodworkingschool.com/our-courses/ mixed into the text. I suspect everything this year is full but am not sure.

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