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Thread: shellac question

  1. #1
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    Default shellac question

    I use a lot of shellac. Primer under varnish, sanding sealer for furniture and as a final finish.
    I have recently completed a commission for a client and had to match an existing finish, a mahogany tint on some cherry. I blended garnet shellac with some commercial tints and got it just right. Took more than a couple tries to get the color to match but I got there.

    I will be making more furniture for the same client and will require the same finish, but its going to be a while.
    My question...rather than starting all over again and trying to mix the same color; Im thinking of simply letting the shellac in the pot just harden. At some point left uncovered the alchohol will evaporate will it not? Im hoping to just pop the hardened shellac out of the pot, wrap it up and put it away.

    What say you finishers?

  2. #2
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    Default Re: shellac question

    Could work. You might need to grate it back into flakes to redesolve it. Let us know how it goes.

  3. #3
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    Default Re: shellac question

    Put a lid on the jar or preferably a plastic lid on a plastic container as shellac is a good glue .... but you could pop the plastic lid off.
    '' You ain't gonna learn what you don't want to know. ''
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  4. #4
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    Default Re: shellac question

    Ziploc bag in wide-mouthed container so you can get it out easily?

    .
    .

    “What use is a house if you haven’t got a tolerable planet to put it on?”


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  5. #5
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    Default Re: shellac question

    Not sure what to say. Lotsa questions.

    1. Are you saying you have enough of the original batch of tinted shellac to do the balance of the upcoming work? If not - you'll have to mix up a new batch anyway, no?

    2. I keep a 'Finishing Notebook' in my finishing room. In it - I record what finishes went on what projects. I also record the formulas used to achieve any particular color match. If you do that - then mixing up the next batch will be easy enough. If you don't/didn't - I recommend it for the future.

    3. Is the shellac the 'final' finish then? Or will you topcoat it with something clear, and more durable?

    4. I find that 'toning' - the process of putting tinted film finishes on to achieve any particular color-match - is problematic. I'm curious why you went that route instead of using dyes and stains to get there... then a clear film finish.

    In terms of your strategy - yes, it's easy to reconstitute shellac with denatured alcohol. I wouldn't deliberately let it dry out. I'd seal it up the best I could with minimum fuss - then just bring it back to brushing/spraying consistency when it was needed.
    David G
    Harbor Woodworks
    http://www.harborwoodworking.com/boat.html

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

  6. #6
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    Default Re: shellac question

    I will have to eventually mix another batch, thats not really an issue. There is enough left over that I dont want to toss it. I have shelves of blended finishes from a variety of projects.

    Its more a question of whether or not its easier to store dry material than wet. A lump of dried shellac can go back in the drawer in a ziploc with the bags of flakes and buttons as opposed to living on the shelf with all the other jars and cans and plastic take-out soup containers.

    The original pieces were finished with a tinted film so staining or dying the new wood was not really an option. One of the new pieces butts up to; is now an extension of one of the originals. Two coats of satin poly over everything to finish and protect....

  7. #7
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    Default Re: shellac question

    I'd put it in something tough like water bottle,then a ziplock bag and put it in the freezer.
    R
    Sleep with one eye open.

  8. #8
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    Default Re: shellac question

    Your plan will work just fine, if that's the way you prefer to store it.
    David G
    Harbor Woodworks
    http://www.harborwoodworking.com/boat.html

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

  9. #9
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    Default Re: shellac question

    Just keep it stored out of direct sunlight or it will tend to not dry properly and remain tacky. I also add a shot of Bloxygen to mine.
    Jay

  10. #10
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    Default Re: shellac question

    I have always read and understood that old shellac will not dry properly. I don't know the reason for this. I always assumed some chemical reaction was taking place. Jay's remark about keeping it out of direct sunlight is news to me. I'm certainly not saying it isn't so. Just that I haven't heard or read of it. If something is happening to the already mixed shellac, letting it dry may not stop it. Should you carry on with this endeavor, doing some finish tests with the reconstituted batch would be prudent.

    I know from experience that it takes a good while for a tub of shellac to dry out even when left with the lid off.

    Jeff

  11. #11
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    Default Re: shellac question

    It would dry a lot faster if you spread it out as thin as practical. A plastic sheet on a cookie sheet might do the trick. I wouldn't dry alcohol in an oven, especially not a gas fired oven. Once dried, it should keep a lot better.

    One question about color matching on cherry. How do you compensate for the cherry darkening after finishing?

    Quote Originally Posted by jpatrick View Post
    I have always read and understood that old shellac will not dry properly. I don't know the reason for this. I always assumed some chemical reaction was taking place. Jay's remark about keeping it out of direct sunlight is news to me. I'm certainly not saying it isn't so. Just that I haven't heard or read of it. If something is happening to the already mixed shellac, letting it dry may not stop it. Should you carry on with this endeavor, doing some finish tests with the reconstituted batch would be prudent.

    I know from experience that it takes a good while for a tub of shellac to dry out even when left with the lid off.

    Jeff
    A chemical reaction is taking lace. I have to agree with Jay about not storing in the sun. Shellac should dry hard more or less crystallize, but that can be prevented by contaminants or breakdown products formed by a chemical reaction which explains why old shellac or shellac stored in either a liquid solution or in the sun (UV degradation) will fail to dry properly. Alcohol is almost impossible to dry completely and any moisture in the liquid will slowly break down the shellac. (Dry as in the complete absence of water from the liquid alcohol.)

    https://en.wikipedia.org/wiki/Shellac
    "Liquid shellac has a limited shelf life (about 1 year), so is sold in dry form for dissolution before use. Liquid shellac sold in hardware stores is often marked with the production (mixing) date, so the consumer can know whether the shellac inside is still good. ... Alternatively, old shellac may be tested to see if it is still usable: a few drops on glass should quickly dry to a hard surface. Shellac that remains tacky for a long time is no longer usable. Storage life depends on peak temperature, so refrigeration extends shelf life."

    EDIT
    Quote Originally Posted by Jay Greer View Post
    Just keep it stored out of direct sunlight or it will tend to not dry properly and remain tacky. I also add a shot of Bloxygen to mine.
    Jay
    Bloxygen is 12 grams of argon for $12! That is 6.7 liters, less than 1/4ft³. Propane gas is slightly heavier than Ar (Ar works because it is a heavy gas), just as inert (inert to the paint, I know it is flammable) and costs $3 for 14.1oz, 400g, which is 14 ft³. If you have a gas grill propane is almost free compared to Ar.
    Last edited by MN Dave; 08-03-2017 at 10:49 PM. Reason: Not worth bumping the thread for this.
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  12. #12
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    Default Re: shellac question

    Shellac is sensitive to temperature and UV. Is must be kept in a cool, dry dark place. The supplier I use wont even ship dry shellac this time of year because of the potential for heat damage in transit.

    I store all my shellac in double ziploc bags in a drawer that is down close to the shop floor where it never really gets that warm. Squeeze all the air out of the bags when I seal them up. Old mixed shellac can be problematic which is why Im thinking of drying it to store it.

    I am going to try a small batch and see what happens. Spreading it out on a cookie sheet might make more sense than letting it harden into a chunk, I hadnt thought of that.

    I will let everyone know how it goes.

    The original pieces are cherry with a tinted finish so there was no issue with the new pieces darkening. I just did the same thing using tinted shellac.
    Shellac can be thinned way way down and can be used like wood dye to very subtly tint a number of woods and the color can be brought up gradually with succesive coats.

    I am by no means an expert; more of a half talented hack and I would defer to others like Jay for anything like professionsl advice....

    Thank you all for your responses, stay tuned.

  13. #13
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    Default Re: shellac question

    How about some picchers of the junction? Sounds like a boo'ful jawb!
    Hands too small: Can't build his Wall!

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  14. #14
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    Default Re: shellac question

    I'd give it a shot but flakes and tint and evaporation sound iffy to me. Never heard of the proposed method.

  15. #15
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    Default Re: shellac question

    I, mostly, use flake shellac for my French polish work. Analine dye powder is a good choice for tinting, if needed. I know about how much to mix at a time so, I rarely have storage problems. The Bullseye, pre-mix, brand that is now on the market seems to have gotten away from drying problems with older shellac that has been stored for a while. Mixing my own cuts material cost by about 60%. I do have a one pint mason jar of amber shellac I keep on the side bench with a disk of door skin to cover it. It has a hole in the middle for a one inch quill sign brush that hangs in the shellac. It gets used a lot and I just add new shellac to the old. No problem.
    Jay

  16. #16
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    Default Re: shellac question

    Ditto... I have a few jars of made-up shellac both blond and amber, and always use ethyl alcohol partly because we can't easily get denatured alc here...I always used meths in UK, but it does have more water, pyridine to make you puke if you drink it , and purple dye so its obvious...perhaps these are factors in the above problems.
    I have always just kept made up shellac in a jar, adding more alc and more flakes as necessary. I don't really see an advantage in storing dry. if the lid gets glued on invert the jar in a few mms of alc for a few minutes. To let it dry completely into a cake and redissolve in the future seems a load of work.
    If the idea is to maintain a colour you've achieved for the future then make up enough now while you have it right, and just store it. If you make it up in the future you'll still have to fiddle around getting it right anyway. To redissolve a dried cake the colour might be right but the dilution alc to flakes will affect the tone and hue so you'll have to mess about anyway.
    I'd just make up a big enough batch now and store it in several smaller jars if space isn't a problem, and keep the jars with as little airspace as possible.
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  17. #17
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    Default Re: shellac question

    turf it and start anew. dissolved shellac does not have a long shelf life. one is always asking for problems with old shellac.
    ron

  18. #18
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    Default Re: shellac question

    One of the properties of Bloxygen is that very little of the gas is needed. I do a lot of varnish and paint work in a years time but a single can is all I usually use.
    The fact is that it takes only a tiny squirt under the almost closed lid. The gas is heavier than air and spreads out over the surface of the contents and seals it from the O2.
    Jay

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