Preping Shellac

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ttalma

ttalma

Well-known member
I am preparing to finish a chair I made, and will be using shellac flakes for the first time. I have used the premixed stuff before. But I have a few questions about about the flakes.

I am going to make what I would call a 5 pound cut  (1 part flakes to 4 parts alcohol)

I am not sure what alcohol to use, I've been told any is fine, but Grain is the best because of its high % of alcohol content. But I found out at the liquor store yesterday That in NY you can't buy anything higher than 100 proof (50% alchol by volume) so I got some 100 proof vodka. Is this okay to use? I don't really want to use rubbing alcohol cause the smell bothers me.

How long should I expect it to take for the shellac to disolve?

Do I need to filter the shellac after it's disolved?

Any other tips?

I have some golden Taklon brushes I'll be using and I'm going to practice appling to some scrap so I'm more concerened with the prep than the application, but I would be willing to accept any advice.
 
For 20+ years I have been using the alcohol from a hardware store or home center and never had one problem.  A 5 lb. cut is a thick mixture and I am not sure why you want this.  Myself and most others use a 2 lb. cut.  The time to disolve will depend on the type of flakes.  My orange shellac flakes will take less than a day but the dark garnet shellac (from Olde Mill cabinet Shoppe) takes 3 days to completely disolve.  I suspect your 5 lb. cut will take days (less alcohol).  For any flakes, stir it often.  When you notice no clumbs sticking to the stick wait a little longer and then filter it thru a fine painters mess filter.  I buy mine from Woodworkers Supply, www.woodworker.com. 

Tip: do not bruch on shellac on humid days or it may turn milky white.

Dennis Bork
Antiquity Period Designs, Ltd.
 
No, 100 proof grain alcohol will not work to dissolve shellac - there's WAY too much water in it.  Save this for making martinis or hunch punch, and trot down to the hardware or local paint store and buy some 100% denatured ethanol.  It's far cheaper, and the denaturants won't interfere with the finish (or poison you unless you drink it).

As Dennis alluded to, what you're describing is not a 5lb. cut of shellac.  I haven't measured this out exactly, but 4 parts alcohol and 1 part shellac by volume will give you something like a 1/2 lb. cut, which is really too weak to be used as a finish (though it could be used as a pre-stain conditioner).  A 2 lb. cut for shellac is about the standard for using it as a finish, though I regularly use a 1.5 lb. cut and more coats.

A 1 lb. cut of shellac is defined as 1 lb. of shellac to one gallon of alcohol.  You don't have to weigh it (you can just "eyeball it"), but I find an el-cheapo electronic kitchen scale from Bed Bath and Beyond very useful to measure and mix shellac.  These scales usually measure in grams, which is easier to use than fractional pounds (often displayed as just tenths of a pound, which isn't accurate enough for just a little shellac) to measure the shellac.  There are 454 grams in a pound, and 128 fluid ounces, 4 quarts and 8 pints in a gallon, so to mix up a pint of shellac at the 2 lb. cut strength, you need 57 grams of shellac and one pint of denatured ethanol.

To make the shellac flakes easier to dissolve, you can use a small coffee grinder to turn the flakes into a powder.  Add only a little of this powder to the (glass) jar with the alcohol, stirring frequently, then a little more, etc... until it's all dissolved.  Adding all of the shellac at once results in a gooey mass at the bottom of the jar which will delay the dissolution, though it will all dissolve after a couple of days.

Finally, don't use "rubbing" alcohol to dissolve shellac.  Rubbing alcohol is a mixture of 60% isopropanol and 40% water, and even if it didn't have the water in it (which is bad for shellac dissolution), shellac has a much lower solubility in isopropanol than ethanol (the primary constituent of "denatured" alcohol).  It's also considerably more expensive than ethanol.
 
Tim,

I'm no expert, but it seems to me that people get too caught up in the "pound cut".  I think years ago Jeff Jewitt or Mario Rodriguez (lecturers at RWS) said to put the flakes in a jar and pour in alcohol to 2x the flake level (maybe 3x).  If this appears too thick to brush easily or all the flakes don't disolve, just add more alcohol.  I've done it that way every since.  If all the flakes don't disolve, I asume the mix has reached saturation and I add more alcohol.  Lately I tend to make a close to saturated solution, then pour some into a smaller jar and thin it as required.

I've also done the coffee grinder route, and it definitly speeds up the process.  In that case I go about 6:1 ratio. If the jar gets gunked-up over time I will pour the mix through a 10 cent paint filter.

I understand you can't buy 100% grain alcohol in NY.  Not sure about PA, but I believe Bess can get it thru Olde Mill.  I bought some through a place in Texas that Don Williams suggested when he was at RWS a couple years ago. I really haven't noticed a difference between pure ethanol, Behnkol or the no-name shellac thinner from the hardware store.  However I do like the idea that the 100% alcohol hasn't been denatured (poisoned).

Once the container is opened, the alcohol will absorb water from the air.  Don suggested filling the container with glass marbles to minimize air space in the container.  I bought marbles, but have been too lazy to try it.

Be careful on the "color" of the shellac.  I used seedlac on a walnut box, and it looked great after 1 or 2 coats.  After several more, it ended up looking like mahogany with a reddish tint.  The grain in the crotch lid almost disappeared.  I ended up stripping the shellac off and re-doing with orange shellac.  I believe Allan Breed told us (again at RWS) he uses seedlac on mahogany, which is what prompted me to try it. So if you use a darker shellac for a certain look, you may want to start with it, then switch to an extra light shellac once you are happy with the color.
 
I will add a little.  Also, I have some references to useful information on my web site that are courtesy of some other fine folks.  Look under materials and techniques:  www.americanperiodfurniture.com

But here goes:
    Like was mentioned, orange shellac is ...well, orange, and repeated coats change the color.
  There is blond shell which is close to a neutral color, imparting very little color of its own, but does some.
  Garnet and dark garnet are a little more brown
  Seedlac is my favorite, but it too will change the color.

Measuring is not that much of a hassle with simple tools.  1 1/2 to 2 lb cut are most common as noted above.

The thing about measuring (to some minor level of accuracy) is you know what you are working with.  And this may be helpful for a beginner with shellac.  Like mentioned, many just cover the flakes with alcohol and that is good.  But of course that does not work if you are grinding the shellac.

Good luck.

Ken

I use grain alcohol and much prefer it, but denatured works great too.

 
About the application - You don't say what sort of chair you're finishing, but you may find that brushing a chair with a lot of intersecting planes and angles to be quite a challenge with shellac.  That's not to say that you shouldn't use shellac - it's entirely appropriate for a period piece and it looks good, only that the brush part of the equation may give you a little trouble.

If your previous experience with film finishes has been polyurethane or alkyd varnishes, there's a world of difference with shellac.  In particular, you can avoid runs and sags in poly or alkyd varnish by "over brushing" (going back over a wet surface with a brush).  You can't do this with shellac, as it dries so quickly that brushing back over it will usually induce a jumble of deep brush marks.  Further, if you see a run, you have to take care of it immediately - there is no opportunity to complete the surface you're working on and go back and remove the run with a brush or a rag.
 
I've prepared Shellac from flakes for years. I usually prepare a 1 lb cut for conditioning surfaces and a 2 lb cut for building a finish coating. I use my wife's inexpensive digital kitchen scale to weigh the shellac flakes and I use one of her glass measuring cups to measure the alcohol volume (yes I wash it thoroughly when I'm done). I like to prepare shellac in a clean glass peanut butter jar. Its a convienent size, has a wide mouth, and is disposalbe when I'm done. I've actually used both Bekhol and denatured alcohol from the hardware store for preparing shellac. Both work quite well and I have not noticed a difference between the two. I agree that grinding the shellac flakes does speed the disolution process.

I like to apply shellac using a cloth pad. This works well on large surfaces. For fine details in carvings and mouldings I find that an inexpensive artists brush does the job nicely.

As for the hazards assoicated with denatured alcohol, there's some good information online. Denatured alcohol is ethanol + an additive that makes it unsuitable for human consumption. The most common additive is methanol (another alcohol molecule that is poisionous). However, many other additives are used depending on the intended use of the denatured alcohol. If you are concerned about the hazards of a particlular denatured alcohol try to find a Material Safety Data Sheet (MSDS) for the product that you have. They are usually availalbe online. If you can't find one, call the chemical manufacture. They are required to provide one if you request it. The MSDS will explain the hazards associated with the product as well as permisiable exposure levels.

I figure that from the shellac's point of view pure ethanol looks pretty much the same as ethanol + 10% methanol.
 
Thanks for all the advice. I picked up the ethanol. But haven't done more than set it in the shop. I plan to get in the shop Wednesday to mix up the shellac. And hope to start finishing Saturday. I have a few small details to complete before the chair is ready.

It's the french chair I had posted some questions about earlier. So there's actually not a lot of mahogany.

The shellac flakes I'm using are garnet flakes from the olde mill. all of the mahogany is from the same piece of wood, so the color matches quite well so I shouldn't have to worry about dying the wood. I'm looking forward to finishing this and starting the finish on my card table that's been complete for two years witout finish. (I plan to use blond for that).
 
Thanks for all the advice, The ethanol worked great. I did use a scale to get the ratios, and over night 90% of the Shellac disolved, and two days later it was all dissolved.

I used a coffee filter to filter it, which worked fine, and the shellac appears to be particle free.

I've put a few coats and and it looks great.

for those inquiring minds, I also decided to try using the vodka to disolve it. So I mixed a small amount. And after sitting in the vodka for 6 days, most of the shellac remains undisolved.
 
That's because of the water in the vodka.  Everclear (95% or 190 proof) will work, though it's expensive.  Funny thing is that if you wish to recover your vodka, you can just pour it off of the undissolved shellac and mix a drink with it.  Shellac is an approved food ingredient, and a good number of pharmaceuticals and vitamins use it as a pill coating.
 
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