Salvaging(?) 151
Given my possession of a full case (~3 gallons) of 151 proof grain alcohol, useless for much of anything but cleaning brushes, I decided to try to salvage it if possible.
Mixing some varnish with pure 151 was the obvious place to start. I mixed up a pint of the shellac lemon resin as normal for a 190 mix, then let it sit for several days to see if it would go into solution.
It did not.
I next added some 190 to the pseudosolution, estimating that a proportional addition would result in a roughly proportional increase in the proof/solubility parameter. By that metric I was able to achieve complete solvation around the 170 proof level. A couple days at that level and I had a container of shellac varnish.
I brushed it onto a sample panel with vaguely successful results. The first application, in particular, had simply horrible brush-feel, and the result was not promising.
But, with stubborn determination I applied another half dozen coats in a two hour period, and two days later it had fused into something resembling a finish. It would not have been an acceptable surface for a typical finishing project, but I charged ahead to see what, if anything, could be resultant from taking the exercise to completion.
With the brushed out surface cured for a few days, I scraped it over half of the panel surface, then detailed it with my “go to” step of rubbing it with Liberon 0000 steel wool and paste wax, then buffing the surface after a couple hours.
The end result was not awful. It doesn’t mean that I’ll be using much 151 proof grain alcohol in varnish making, but its’s good to know that I could use it if I really needed to.
Hi Don,
Being a Ph.D. organic chemist and a woodworker, I have an idea that might not be too difficult. I woudl get some copper sulfate hexahydrate and stick it in an oven to drive off the water (it will go from blue to white). From there, I would add the dry copper sulfate to the 151 proof. Swirl on occassion. When the bulk of the copper sulfate has turned blue, it has absorbed as much water as it will. Decant off the solution and add more dry copper sulfate. Eventually, you will get the 151 proof to 190 or better proof. If you keep the copper sulfate and let the ethanol evaporate, you can reactivate it in the over but be careful the ethanol is removed first so you don’t get a big boom. I don’t like molecular sieves for ethanol as it tends to leave it cloudy. Happy to chat more.
It may not be worth it, but the way to easily remove water from alcohol is with 4A molecular sieves. This is a solid that can absorb about 20% of its weight in water without taking up alcohol, and later can be regenerated by baking in the oven to drive off the water leaving it as is started for reuse.
You would add pellets to almost fill the vessel, swirl, cap, and let it stand overnight. Next day drain off the drier alcohol for use, either being careful to not pour any dust, or filtering the alcohol through a coffee filter or something. Let the sieves dry out (or rinse with water) to remove alcohol to avoid fire before baking in the oven to regenerate. Up to about 575F you are removing more and more tightly held water.
If the alcohol is not dry enough after one treatment, do it again. If you activate the sieves at 575F, you can get water levels below 1PPM by sequential drying, but that’s ridiculous overkill for your purposes.