Acrylic Paint removal from Plastic

[Arragonis]

I have some plastic which I mistakenly sprayed with black acrylic matt paint a couple of years ago. The plastic is the soft stuff models are made of - its actually a car model I was painting at the time. I need to remove the paint without damaging the plastic and removing detail so I can paint it correctly. I've tried oven cleaner which removed enamel paint without any issue but is not doing much for the acrylic.

Anyone any ideas what may be safe to use ?

[Thymeclock]

Originally Posted by Arragonis

I have some plastic which I mistakenly sprayed with black acrylic matt paint a couple of years ago. The plastic is the soft stuff models are made of - its actually a car model I was painting at the time. I need to remove the paint without damaging the plastic and removing detail so I can paint it correctly. I've tried oven cleaner which removed enamel paint without any issue but is not doing much for the acrylic.

Anyone any ideas what may be safe to use ?

You have two alternatives: solvents or abrasion.

The trick is to find which solvent will dissolve the paint without harming (melting) the plastic. I doubt that any solvent will work, as acrylic paint itself is related to plastic composition. Start with the least volatile solvents and progress to the more aggressive ones. Begin with naphtha (benzine). If it does nothing, try MEK (methyl ethyl ketone) or lacquer thinner, which is a blend of solvents. Don't try acetone alone, as it almost surely will wreck the plastic. Test cautiously in an inconspicuous area.

I'd wager that any solvent that dissolves the paint will also dissolve the plastic. The alternative is to use ultra fine sandpaper or rubbing compound (as a follow up) to wear the paint off through abrasion. If you are going to repaint the plastic it won't matter. But it's highly likely that removal of the existing paint will leave you with a dulled surface, no matter what you use.

[slowmover]

My same mistake yesterday. And the answer is sadly what I expected.

[Ladogaboy]

Originally Posted by Thymeclock

The alternative is to use ultra fine sandpaper or rubbing compound (as a follow up) to wear the paint off through abrasion. If you are going to repaint the plastic it won't matter. But it's highly likely that removal of the existing paint will leave you with a dulled surface, no matter what you use.

You could actually use something like Turtle Wax for this... enough elbow grease, and the paint should come off.

[Peter7307]

Try a post on a dedicated modeling site such as Armorara or FineScale Modeler.

This must have happened to posters on some of those sites previously.

Peter.

[Arragonis]

Originally Posted by Ladogaboy

You could actually use something like Turtle Wax for this... enough elbow grease, and the paint should come off.

I tried this approach with a cutting paste but its a little too fiddly.

Thanks to all for the suggestions. I eventually went with a white plastic primer and then a quick run with the cutting compound once hard - that restored the colour and I could paint it again. It didn't fully match but the parts which are discoloured are underneath and inside, so it should be OK.

[euromodder]

In a past life I used to build models.

Acrylics should come off with oven cleaner though there are a few issues.

- Oven cleaner isn't what it used to be due to health regulations, it's now far weaker stuff and less suitable for paint removal (less caustic soda in there).
Put the parts in a plastic bag, spray, seal the bag, let it sit overnight.

- Caustic soda dissolved in hot water should do the trick - let it cool down to no more than lukewarm before putting the model in it, or the plastic will warp.
(Gloves, eye and breathing protection highly advised when handling and dissolving solid caustic soda ! From a former employment, I recall a delivery driver being hospitalized after getting a single chip of caustic soda in his shoe, he didn't realize it until hours after the delivery. Nasty stuff.)

- IPA or iso-propyl-alcohol is a good thinner for acrylics, soaking the model in IPA will weaken the old paint.
(Cover the container containing the IPA and model with something that seals it off or the IPA will evaporate quickly - not too healthy either.
Note : so-called rubbing alcohol may contain ether which will attack the plastic - check the ingredients before using on plastic.)

[Arragonis]

I tried the oven cleaner trick - that worked on the enamel paint and got the whole thing cleaner than it was before I started except for the part painted with Acrylics. It seemed to work on some parts but the rest would not move.

I'll take a look at the other options if I do it again.

Models is reasonable therapy when the gales are on. Now work has started again I can see this one going back on the shelf for another 12 months - I bought it in 2007...

[euromodder]

Originally Posted by Arragonis

I can see this one going back on the shelf for another 12 months - I bought it in 2007...

Perfectly normal