Shellac not dissolving

[tytower]

I am looking for a chemist or that type of level of knowledge.

I have shellac flakes that will not dissolve in alchohol at all. It is probably about 5 years old and has been kept in a sealed jar but in a moist environment exceeding 80% humidity every day for most of the day.

I have tried other solvents such as paint thinners , acetone and mineral turps etc. to no avail. Anybody got any ideas about what is going on here? I want to save it . I have about 5 kilos of it.

[ubeaut]

G'day tytower - This usually means you are using rubbish metho straight off the shelf at the supermarket or cheap hardware stuff which is for cleaning windows or lighting a stove, etc. Could be wrong but just about bet that's the problem.

You need to use at least 95% Industrial Methylated Spirits (ethanol) 100% would be better.

If it isn't the metho and I'll bet it is, then it could only be that they are antique shellac flakes. Could have been around for many many years before you got them but still should disolve in GOOD metho.

Cheers - Neil

[ubeaut]

Forgot.... Wast of time trying to mix it with anything else.

If you want to test your metho put a little into another bottle then add a very small amount of turps and shake (the bottle not you) if it is at all cloudy then it's contains water and is useless for melting shellac

[Claw Hama]

Neil, great tip testing with the turps.

[kevinmcc]

Neil,

I almost hesitate to ask.. Where does one buy 100% industrial grade metho? Also, are we talking ethanol, as per your post above, or is it methanol?
cheers
Kevin

[ubeaut]

Not Methanol - NEVER METHANOL bloody dangerous toxic stuff.

Ethanol (in Australia) is alcohol end the other name for methylated spirits.

Getting harder to get 100%IMS but 95% should do if it's a brand name or from someone you know and trust. I have a few hundred litres of 100% in hand pretty well all the time but am a bit loath to sell it for a couple of reasons.

1. Our price is reasonably high as every litre we sell is a litre we loose from a Shellawax mix, which is why we keep it.
2. More importantly it's expensive to freight because of Dangerous Goods surcharge.
3. I only to sell it in 5 or 25 litre lots, again (mainly) for freight reasons $20 per shipment for DG surcharge is better spread over 5 litres or 25 litres than 500 ml and our only other bottle sizes are 250ml or 500ml. Waste of time.

Most GOOD paint shops should be able to get it if they don't have it, but many won't because they can't be bothered. Most of the better Mitre 10's used to keep it on the shelf but It appears that Diggers who supply Mitre 10 may not have the 100% any more instead opting for 95%.

Hope this is of some help.

Cheers - Neil.

[Claw Hama]

Oh and always keep the lid on your metho or it will soak up any humidity in the air and end up wet anyway.

[bobbelfield]

http://antiquerestorers.com/Articles/jeff/shellac.htm

Dry shellac flakes store indefinitely under proper conditions, but contrary to what you may hear, it won't store forever. Given enough time, especially under hot, wet conditions, dry shellac reacts with itself to form polymers that are insoluble in alcohol. Shellacs that have been dewaxed are more prone to this.

Dissolve dry shellac flakes in denatured ethanol, which is sold in most paint stores. It also dissolves in methanol, butyl and propyl alcohol. Methanol will evaporate the quickest, followed by ethanol, butyl and propyl alcohol. The last two alcohols, butyl and propyl can be added to shellac dissolved in ethanol in small amounts to act as retarders, which make the shellac stay wet longer for better application (like brushing). Lacquer retarder can also be used. I do not recommend using methanol as a solvent because it is very toxic. In some older finishing books, methanol is referred to as wood alcohol or methylated spirits, but its use is discouraged.
Once dissolved in alcohol, shellac eventually esterifies as mentioned above. Although I have successfully used 12 month old shellac, shellacs older than 6 months should be tested. Pour a small amount onto a piece of glass. If not dry to the touch within 5 minutes, it should be discarded. For this reason, it's a good idea to make up only enough shellac to use within a six-month period.

[banksiaman]

I get my Metho at the Hames Paint store at Narellan (NSW), It's the right stuff for Shellac. It costs a lot more, but it works. Don't know if you have Hames stores in Qld, I just asked for Metho for French Polishing, and it was right next to the bags of Shellac. From memory $20+ for 5l, but don't quote me.

Chris