Shellac follow up

Re: Shellac follow up

Bill, I am unsure whether “methylated spirits” is an Australian/British/Commonwealth term, but I do not hear it mentioned on USA forums. Perhaps it has a different name? It is essentially denatured alcohol with an additive to discourage it being consumed. The local version is clear.

Link: https://en.m.wikipedia.org/wiki/Denatured_alcohol

At any rate, this is what I use - cheap, easily available, and it works well. 

Regards from Perth

Derek

Re: Shellac follow up

It seems extra expense and effort is being devoted to avoiding the most convenient solvent- 50/50 methanol/ethanol available everywhere.  Just considering the performance of this mix, what is its disadvantage that has been revealed by comparing it to 95/5 ethanol/water or 100% ethanol?   

I switched to isopropanol after reading a comment by Bill Anderson, appended to a post by Chris Schwarz. Bill is a planemaker, tool historian, and former EPA scientist (not sure what his area was). Here is his comment in full:

Chris, after my bone marrow transplant, I have made a great effort to eliminate high VOC solvents from the shop. As you mentioned, DNA is a poison because of the methanol in it. Everclear is also a poison but is a socially acceptable one. These alcohols were easily metabolized to aldehydes which are very reactive to proteins and nucleic acids. I use 99% isopropanol. This has one more carbon than ethanol, so evaporates just a bit more slowly. It is sold in pharmacies and grocery stores (I get it from bulkapothecary.com) and is generally regarded as safe (GRAS)–note the use on babies butts! The advantage of isopropanol is that the solubility of shellac in it is no different at the levels we use (0.5 to 2 lb cut), and because of the lower volatility, the flow out of brush marks is very improved. A friend in Arizona emailed me yesterday saying that he is still able to shellac, though only in the am!

So summing up from Bill, Chris Schwarz, and others, it seems the main knock on the hardware store (usually Kleen Strip) brands are that they're (1) not as good at dissolving the flakes; (2) are more toxic; (3) have short open time and poor flow compared to isopropanol.

I haven't done enough research to confirm nos. 1 and 2, but as I said earlier (and B.T. has confirmed), no.3 definitely seems to be true.

P.S. So pleased we can now insert hyperlinks!

Re: Shellac follow up

"Methylated spirits" means methanol.  Yes methanol is toxic and that's the point: denatured alcohol has something added to make it undrinkable so no alcohol tax need be collected as is for everclear.  Various toxic things are used.

Interestingly, the antidote for methanol poisoning is ethanol because the biochemical transformation that makes methanol into formaldehyde prefers ethanol and its transformation to the less toxic acetaldehyde that can itself be transformed into nontoxic acetate.  As mentioned, isopropanol is converted instead to acetone.

At the low amounts of methanol usually used (5%) I wouldn't worry about methanol as a denaturant, particularly if you ventilate well during use.  The 50% methanol sounds bad to me, and is probably used because it's cheaper.  Water is still cheaper and can be found at 30% in some rubbing alcohol (isopropanol) -- I'd use at least 90% isopropanol.  In ethanol as was mentioned it's expensive and not necessary to go below 5% water, but it is not likely to have benzene in it today.

Re: Shellac follow up

We can't get denatured alcohol in California any longer.  I buy it by the gallon when I travel to Arizona or Oregon.  I'm looking for an acceptable alternative.  I use it for airbrush cleaning.  I have found a camp stove alcohol works well enough.  Slower evaporation and lower VOC.  Seems to work OK for dyes as well.

Re: Shellac follow up

most convenient solvent- 50/50 methanol/ethanol

Now that I know the hazards I don't consider it convenient. I did find lower methanol mixes some time ago but they are pretty heavy on it now. I pony up the extra money for everclear.

The last time I looked at the Zinsser shellac SDS there was no methanol in it at all. For jobs that are appropriate for that it is reasonable in price and safety.

Re: Shellac follow up

 I've read that camp stove alcohol is hit or miss where cleanliness is concerned. It seems to have floaters drifting about. Doesn't matter to me because I see floaters all the time, so I use whatever the Borgs have--at outrageous prices. I noticed today that Lowes has two brands on their shelves.

What about using Acetone for dissolving shellac flakes? Even as a thinner for varnish?

Bruce, 

in the process of buying the cheapest kitchen base counters and clearance top on his Visa. Wife will find out when the contractor arrives......  This all stems from faucet and sink that can't match anything sold now.

Re: Shellac follow up

Acetone is pretty nasty stuff, I do use it on occasion, but would not use it for this.  One thing it has against it is that it typically contains a small amount of oil.  I used to use it to clean things squeaky clean, and it would seem to get there, then the glue bond would fail.  I started doing a double clean, finishing with alcohol.  Worked great.  It wasn't until later that I learned about the oil contaminant in acetone.

Re: Shellac follow up

I mostly French polish shellac, so my choice of solvent is based on what is easiest to polish, and what is safest for my skin.  I do spray, but have never sprayed shellac.