I have an ancient loco (photo below) that I would like to repaint. The question is how to strip back to bare metal without everything falling apart.
The loco in question is a GEM Vari-kit (probably Peco branded at the time I bought it) on a Minitrix dock tank chassis. The kit is assembled with Araldite Rapid and some details (such as handrails) superglued. Aside from the rather gooey paint finish, the weathering, which I did as a varnish wash, has darkened dramatically (much darker than the photo suggests). It's not a great model, but I'm attached to it and I'd like to repaint it.
My usual go-to for paint stripping is caustic soda, but I know that breaks down epoxy and would convert the loco back into a kit. (OK, I know it only has about half a dozen pieces but I'd still prefer to keep it intact!) I've used brake fluid in the past but not on anything glued together, so I don't know how it would behave.
Any suggestions?
Ian
I believe Dettol has been used with success by some (but I have not used it myself)
Mr Muscle oven cleaner.
Quote from: hughn on May 07, 2021, 20:36
I believe Dettol has been used with success by some (but I have not used it myself)
I've used Dettol (actually Tesco or Asda own brand equivalent) on Warhammer plastic soldiers. It works OK if left to soak for a long time. The danger I found with not leaving it on long enough so the paint simply floated or washed off in warm water is that the paint turned very gooey and attempts to remove it just spread it about.
I'm not sure what it would do to epoxy glue though. I was surprised to learn that caustic soda affected it. I suspect then that oven cleaner would do so too then. Perhaps some of the supposedly plastic safe paint strippers might do it. I used some I got at a model railway exhibition once (Soak and strip? Strip Magic? - I've forgotten) but it was expensive for bulk use.
I've heard of IPA being used. Possibly the way forward is not to soak but dampen and scrub off the paint so it does not have much time to attack the epoxy. That may be where a solvent paint remover could be better as the paint washes off in thin layers rather than soaking in and more or less peeling off the swollen and softened paint, as is the case with many paint strippers.
Quote from: hughn on May 07, 2021, 20:36
I believe Dettol has been used with success by some (but I have not used it myself)
I used dettol to strip back an old varikit, but it does soften epoxy glue like araldite - depending on how long you leave it. If you put it in the dettol for a couple of hours you might be OK - keep an eye on what is happening to the paint it should start to either float off or 'crackle' - that means its coming off nicely, but if you leave it in there for 24/48 hours the glue will be able to be peeled off (my model had VERY thick glue which i wanted rid of). Dont know if it will affect superglue.
Wash in warm water with a touch of washing up liquid and an old soft toothbrush should get most of the paint off. Cocktail sticks can help remove the rest in crevices. Model will still smell of dettol.....
Quote from: Ian McAulay on May 07, 2021, 19:21I have an ancient loco (photo below) that I would like to repaint. Ian
While entirely respecting your wishes I have to say that - from the photo at least - it looks a delightful loco. Certainly a bit weather-beaten and showing signs of hard work, but very realistic - especially the muted lining. Spare the Dettol!
David.
Useful comments - thank you.
I hadn't come across using Dettol, but now I know what to look for, there's lots of information out there on the net.
Just to confirm, the major component of almost all oven cleaners is indeed caustic soda, generally with other stuff to make it safer to use and gooey to stick to vertical surfaces. If you don't mind handling a fairly dangerous chemical, caustic soda can still be bought from many hardware shops and is easy to use as long as you take suitable precautions (outdoors, eye protection, gloves and old clothes). It's completely safe on whitemetal. It has to be used with care on mazak as it reacts with aluminium. It's fine on plastic but can make some types brittle. The downside is that, especially at high concentrations, it eats epoxy. (I've disassembles whitemetal kits with it, which is what I'm trying NOT to do in this instance!)
One snag is that I'm not sure what it's painted with. I painted it about 1990, so old school paint technology. I know I used Halfords grey primer as the base coat, but it was probably cellulose not acrylic back then. The black is probably Humbrol enamel, but might be Tamiya acrylic. The green may well be Tamiya acrylic, the red lining certainly is. And I know it's finished of with polyurethane varnish.
It's tempting just to buy another kit and start from scratch!
I'll report back.
Ian
Quote from: clayliner on May 08, 2021, 11:34
While entirely respecting your wishes I have to say that - from the photo at least - it looks a delightful loco. Certainly a bit weather-beaten and showing signs of hard work, but very realistic - especially the muted lining. Spare the Dettol!
Thank you! I'm certainly attached enough to it to want to keep it, but the colours actually look better in the photo (I brightened it a lot in Photoshop). In reality the weathering has darkened to the point where it's white hard to tell that it's green!
Ian
Quote from: clayliner on May 08, 2021, 11:34
Quote from: Ian McAulay on May 07, 2021, 19:21I have an ancient loco (photo below) that I would like to repaint. Ian
While entirely respecting your wishes I have to say that - from the photo at least - it looks a delightful loco. Certainly a bit weather-beaten and showing signs of hard work, but very realistic - especially the muted lining. Spare the Dettol!
David.
I agree, David, it reminds me of the Britannias I saw in '67 and '68, there was green under the muck somewhere but it didn't show up much!
I use methylated spirit to strip enamel paints from models.
Just leave the item submerged over night in a sealed contained, I use an old Tupperware box and in the morning the enamel paint will just peal away, I help this a bit by using a wooden cocktail stick.
The methylated sprit will not affect plastic, so it can be used to remove enamel paint from plastic models as well. I have in the past completly restored re-painted Egger-bahn items to original condition in the past.
However, it will also dissolve most glues, so if the white metal loco has been glued together you will end up with it disassembled into kit form again!
It is not good on acrylic paint.
Quote from: Ian McAulay on May 08, 2021, 11:47
It's tempting just to buy another kit and start from scratch!
In which case why no strip this one down to parts ;)
I can confirm about Dettol, it removes 90% of paint in an hour or so, and 90% of the remainder in another 12 hours, then 90% of that remainder in a couple of days and so on. I normally end up digging out the last few corners with a cocktail stick, but by then the araldite will probably have decayed too.
Having said all that many of my araldite and super glue models from 20-30 years ago are starting to come apart so maybe no matter how much you try to keep the shape it could fall to bits anyway. :(
So, after dithering around since starting this thread in May, I finally got down to stripping the loco.
My first surprise when I got the body off was that it wasn't primed in grey as I thought I remembered. I had started off with a black spray. I would guess that it was either Halfords or Humbrol, in which case, seeing as I did this about 30 years ago, it could be acrylic, enamel or even cellulose. The green was definitely Tamiya acrylic and I have no idea about the red and white. (See photo in the first post in this thread.)
Methylated spirit was suggested as a paint stripper, as was surgical spirit. They are pretty much the same thing as solvents go - 95% and 89% ethanol respectively. I plonked for surgical spirit as we had quite a lot in stock.
On the plus side, surgical spirit removes paint very effectively, if fairly slowly. Also on the plus side, it's not dangerous to skin with brief contact. It's also fully water soluble and biodegradable, so can go down the sink when finished with. (I suspect that the black paint is not cellulose, given how effectively it was stripped by a fairly gentle solvent.)
On the minus side, it loosens Araldite very effectively. It doesn't seem to dissolve the Araldite or make it go sticky, but it breaks the metal to adhesive bond quite cleanly.
I was debating buying a new kit and starting again with this loco, but my choice of paint stripper has made the decision for me! See picture below.
Thanks for all the discussion on this topic.
Ian
That's left a nice clean set of parts.
Just a couple of bit of chemistry I'll mention...
QuoteMethylated spirit was suggested as a paint stripper, as was surgical spirit. They are pretty much the same thing as solvents go - 95% and 89% ethanol respectively. I plonked for surgical spirit as we had quite a lot in stock.
"Methylated" spirit is mostly Ethanol (97%) with the addition of toxic Methanol to 'denature' it - make it undrinkable (in theory) - and usually in the UK a purple dye (crystal violet) to make Mineralised Methylated Spirti (MMS), though one can occasionally purchase a clear version (Industrial Methylated Spirit or IMS).
"Surgical" spirit might also be isopropyl alcohol (IPA or isopropanol) rather than ethanol, and is also something you wouldn't want to drink (in fact IPA can be used as a denaturing agent to make ethanol undrinkable).
QuoteIt's also fully water soluble and biodegradable, so can go down the sink when finished with. (I suspect that the black paint is not cellulose, given how effectively it was stripped by a fairly gentle solvent.)
I'd agree that ethanol and IPA are fully water soluble, but when pouring them down the sink please
please run the tap so that there is a huge dilution of the alcohol as both have the ability to kill animal life in high concentrations even if they are 'biodegradable', defined as being capable of being decomposed by bacteria or other living organisms and thereby avoiding pollution which I somehow think can not be applied to meths or surgical spirit without dilution and certainly can't be applied to any toxic denaturants added.
There will also be the residues of any paint that has been dissolved by the stripping process, so if you are going to pour the used alcoholic stripper down the sink please dilute it with several times it's own volume to approach something closer to the 40% one would find in a bottle of scotch, or even better the 10 -15% found in wine.
Julien Webb (B. Sc. Industrial Chemistry, M. Sc. Instrumental Chemical Analysis)
That's useful information - thanks, Julien.
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.
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
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 (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.
Quote from: GraemeD on July 12, 2021, 15:28
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
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.