enamel paint removal

[Big Jim]

Any one got any idea how best to remove enamel paint from a resin coach kit?
I am itching to throw the lot into thinners, leave it for a few hours and hope for the best but am feared that the resin will be affected.

[MDLR]

I think you ought to steer well clear of thinners and paint stripper - I have a feeling your coach might dissolve!

After doing a test somewhere inconspicuous, I think you might find that a soak in turps (buy a baking tray, or one of those big foil roasting tryays for roasting turkeys to put it in) would work.

[Big Jim]

Cheers Brian,
I will give turps a go.

It was painted nearly 25 years ago using Humbrol paint from the early 1970's (how do I know the age of the paint? My father cleared out the complete stock from a model shop in St. Albans when it closed, I am still using some of it today!)

White spirit doesn't seem to want to shift it, and Humbrol enamel thinners (modern brew) just attacks the resin.

[Peter Butler]

Have you tried a little liquid poly or similar? You know what happens when you try to repair a broken kit.... the paint always comes off!

[GTB]

Any one got any idea how best to remove enamel paint from a resin coach kit?
I am itching to throw the lot into thinners, leave it for a few hours and hope for the best but am feared that the resin will be affected.

There's not a lot of difference in the chemical compositions of paints, plastics and resins. Any solvent or paint stripper that lifts enamel paints could well attack the resin as well.

I use oven cleaner for stripping enamel off plastics, usually the cheapest local supermarket Home Brand I can find. Cheap ones are better, as the more expensive brand names have a solvent added that can affect plastic.

Spray it on, wait half an hour or so and give the part a scrub with an old toothbrush. If the paint was applied thickly, you may need several applications of the cleaner. Some odd bits will still remain in grooves and corners and I use a wooden cocktail stick to dig them out, so the plastic or resin isn't scratched.

As always, do a small test in an area that's out of sight, just in case.

While oven cleaner works well with enamels, it is fairly useless with acrylics.

A solvent that works on recently applied enamels, but doesn't usually attack plastics is methylated spirits. Isn't as good with very old paint though.

Regards,
Graeme

[andymctractor]

From 'Airbrushing for Railway Modellers' by George Dent  page 82 covers Paint Stripping.  His advice is to avoid DIY paint strippers unless your model is wholly metal. (This doesn't mean it is metal with holes in it.)  He advises model paint strippers such as 'Modelstrip', 'Phoenix Precision', 'Finishing Touches' and 'Expro' are formulated specially for use on plastics or other delicate materials.  He recommends testing before use.  Modelstrip is only useful with enamels and won't budge acrylics or factory finishes.    
These model materials are less unpleasant to use than the DIY stuff but you may have to leave the stuff on for longer or do it more times.  He also advises that model paint strippers may destroy glue joints so you may have to check everything at the rinsing stage.
I freely admit I haven't used any of these myself.

Hope this helps.

[maxi-model]

Sodium Hydroxide is the active ingredient in older types of oven cleaner and potions like Modelstrip and the Phoenix product.

Modelstrip is a paste that you apply to a painted surface and then wrap with clingfilm to stop it drying out and becoming inactive, so better for larger items. The Phoenix product is a liquid and works well when used as a bath with smaller component left in it for paint to dissolve/detach. Both excellent products if used as intended. For enamels only.

You can use cellulose thinners, with care, only with resin not other plastics. Apply with an old (non styrene) toothbrush scrubbing the paint vigorously so it comes off. Helps if you have created a "bath" of the stuff to put the piece in then scrub. Work quickly and do not leave the piece in the "bath2 to soak. Clean down with soapy warm water afterwards. Only do outdoors and with a "bumble bee" respirator. I've restored a lot of resin model car bodies for re-painting this way.

Brake fluid is another one that works on automotive paints, e.g. acrylics, similar method to the above, safe to use with most plastics.

Never be tempted to use caustic paint removers, e.g. Nitromors, with anything other than metals.

Note some laquer top coats and 2 pack finishes can cause problems with all the above methods.
.
Been using above techniques for the last 30 years. Max.

[daveyrd11]

I have used brake fluid with success, its slow but doesn't affect most plastics. As usual try on a small area first!
All I did was coat the item in brake fluid, put it in a plastic bag, leave it for a few hours (don't let it dry out) remove the bag, scrub with an old tooth brush and repeat!

Hope that helps

[Big Jim]

Thanks for the advice folks. I will report when I have managed to remove the paint.

[Big Jim]

After failing to remember to pick up a couple of pints of turps on the way home I decided on the brake fluid method.
I had gallon can of the stuff in the garage that had been open a long time so was going to be no use any more. So the coach components (GRS kit, so each section is only 3'' square) were broken down and dumped in a bucket and the brake fluid poured over it.

The enamel is now falling off nicely and the primer underneath is starting to soften.

Wife is out of the house so I can sit and gently play with the mix on the kitchen table!

[andymctractor]

I remember using cellulose thinners to remove several layers of caked on paint off a brass locomotive. I think different types of paint were used and in places it looked like it had been applied with a trowel. Anyway, I wore a face mask and rubber cloves and an old glass bowl. What happened was the rubber gloves melted onto my hands coating fingers with the gunge that gripped and quickly dried before I could clean it off. I had to use neat cellulose thinners to clean off my hands. Not ideal but it seemed to be the only way to get it off. My wedding ring shone like a new pin afterwards but otherwise there was little positive outcome.
It did get the paint off though.

Hope this helps.

[Peter Butler]

I wore a face mask and rubber cloves and an old glass bowl.

Oh, how I would love to see those photo's.....

[MDLR]

Oh,  how I would love to see those photo's.....

PMSL!! (You see, I CAN do modern...............)

[andymctractor]

PMSL!! (You see, I CAN do modern...............)

You will have to explain.  I assume this is some form of communication from Facebook or Twitter or similar which I don't do.  

OK now I know

[Big Jim]

Well it took a week and three changes of brake fluid but all the paint came off. I am certain that the age of the fluid (closed bottle but not sealed) made the process slower.
A good scrub in soapy water and rinse and they will be sprayed and reassembled.

[maxi-model]

A good scrub in soapy water and rinse and they will be sprayed and reassembled.

A mistake lots of people make when prepping for painting. Use washing soda crystals (not the caustic stuff), rinse off with plain clean water and dry with lint free clean cloth to clean up the surface before painting. Oh. and wash your hands and wear those nice cotton gloves when handling before painting. Problem with most soapy stuff is that it has oils in it "so that hands that do dishes can be as soft as as your face......"  So does your skin, you wouldn't look nice without it. Creates a barrier that stops the paint sticking to the surface long term. Max

P.S. Aston Martin's biggest warrenty claim issue - paint coming off the colour matched door handles. Why ? Cos'the guys doing the painting have to open the doors on the completed body units to get at the innards and forget to wear the gloves they are issued. 1 year later off flakes the paint.