Stripping paint from whitemetal

[Graeme Dunbar]

If there is a safe place to do so then one way of disposing of volatile liquids is let nature take its course. I've left solvents out in a covered but well ventilated area and let them evaporate.

If the solvents were in some other product (paint etc.) that's what would happen.


Edit: of course if they were something nasty and could cause harm in low concentrations then they should be disposed of properly at an appropriate centre and not at home.

[Ian McAulay]

Thanks Julien for your chemical expertise and your advice re disposal - all important stuff.

My qualification is merely O level chemistry 48 years ago! However when I  was an associate in a landscape architecture practice, we insisted that all staff had a fairly rigorous training in chemical safety as we had some fairly unpleasant substances stored on the premises. In consequence, I have developed a healthy respect for nasty stuff in bottles. (Even the admin staff had to do this, as did I, even though my job was computer visualisation!).

I had already checked the composition of surgical spirit before I did the stripping. It has a British Pharmacopoeia definition as 95% industrial methylated spirit (ie, as described by Julien: just the ethanol and methanol and none of the other additives that makes the purple stuff you buy as retail meths), 2.5% castor oil, 2% diethyl phthalate and 0.5% methyl salicylate. I'm not sure what the diethyl phthalate does, but I think the other additives are largely there to give it the medical smell and discourage you from drinking it. Anyway, that was the reason for my assertion that methylated spirit and surgical spirit are close to being the same thing when used as a solvent.

I didn't mention that I caught the paint residue in a paper kitchen towel as part of the disposal. There was actually surprisingly little, and all in the form of crumbs and flakes rather than anything gloopy, which is good. However, having had to clean a sink trap out not so long ago, I really didn't want anything down there that didn't have to be there!

I concur with the need to dilute the liquid going down the sink, but as there was only 50ml of waste surgical spirit, by the time I had run the tap long enough to flush the trap out, that was the job done.

I'll post pictures of the reassembled kit and then its eventual new name and paint job.

Ian

[Graeme Dunbar]

Regarding denatured alcohol, B&Q and elsewhere sell (or sold - I've not been there in a while*) ethanol for heaters which might be convenient source for many.

* yes they do:
https://www.diy.com/departments/la-hacienda-bio-ethanol-fuel-2l/540224_BQ.prd


Regarding the hazards of methylated spirits, Big Clive did a Do Not Try This at Home demonstration (caution - strong language)
https://www.youtube.com/watch?v=ep2I3Gf3Sec

His older brother Ralfy (Ralfy.com) has better taste in spirits - mostly.

[Ian McAulay]

Regarding denatured alcohol, B&Q and elsewhere sell (or sold - I've not been there in a while*) ethanol for heaters which might be convenient source for many.

Another product I didn't know existed! It's a useful source if you need a lot of ethanol as its only £8 for 4L, whereas meths is a touch under £5 for 500mL (Home Hardware) and surgical spirit £5.50 for 500mL (Boots). I only needed 50mL for stripping the loco plus another 50mL to do a thorough degreasing before reassembly. How much you need probably largely depends on the size of container you have available as a stripping tank.

Ian

[clayliner]

When I read Julien's comment about surgical spirit possibly being IPA (the other sort) it prompted me to research it further, too, so I dug out the old bottle I originally bought for treating hen's feet and read the label, with the same results as Ian. I had wondered about using it for track cleaning but am a bit worried about the 2.5% castor oil and whether it would leave a residue on the track after everything else had evaporated.

Ian's comments underline how retailers make a fortune by selling cheap industrial chemicals for exorbitant prices in little bottles (even taking into account handling and other costs).

David.