Painting Plastic
I recently tried to paint an AMT car model. It was a disaster. The paint did not stick at all. Nothing I tried worked. Even paints that implied they had primer in them. And Testor paints as well. I thought Testor was very familiar with modeling stuff, so would provide stuff appropriate for this. WRONG! See photo 1.
So I contacted a local expert on building models - Bruce McKinney. Here’s what he said.
Analysis and solution
The problem you may have from paint not sticking may be two fold.
- Many modelers will wash their sprues (From Oxford Languages: a piece of metal or plastic that has solidified in a mold) in soapy water. This will get rid of the releasing oil that is applied to the casting molds to get the plastic to cleanly eject. The oil used on these molds is a very fine light oil - much like a WD40 product. And paint has trouble sticking to oil.
- After washing the sprues to get rid of the oils, and letting them dry completely, it’s best to prime the plastic. Best way to approach this is to use a primer that is specific to styrene. Primer will give a good "tooth" for your paint to attach to.
As for cleaning up the mess I currently have: try a product called Super Clean (See photo 2).
It can be used to strip chrome plating off of the plastic sprues. And it does NOT melt or mar the surface details. Despite the recommendations on the container - Bruce uses it full strength and it goes right to work. Place your item in a plastic storage container; try to cover the entire part with the Super Clean. Depending on the paint you used, it might start to work immediately. Bruce found that full strength Super Clean on the chrome sprues takes about a ½ hour to have a completed naked sprue. Dispose of the used Super Clean; do NOT reuse it. See attached photos of before and after stripping chrome from some parts of an AMT Christie Fire Engine.
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On a side note regarding chrome on plastic model kits: You might consider re-painting with a product called Alclad. It seems this provides a better “chrome” look than what is usually in the model kits by AMT, Revell, and others. But a word of caution: This product needs to be applied as a spray paint. You will need to look up the details on this product and how to use it.
Materials and sources
The following list is just what I have found in stores and on the web. I am not advocating any particular product or vendor. But take into consideration what is said above.
- Products: I think acrylic paints are probably the best for plastic. Here are some brands that I am aware of, with links to the manufacturers if available:
- Testors - all sorts of colors for plastic models
- Tru-Color - all sorts of colors
- Liquitex - A bit pricy. Also, their web site appears focused on fabric (canvas in particular)
- Alclad - For that chrome paint. I only found it on Amazon
- Krylon - Available at most hobby stores, as well as Fred Meyer, Lowe’s, Home Depot, Ace, others
- Super Clean - Available at Walmart, Amazon, Harbor Freight, others
- Locations:
- Tammies Hobbies
- Hobby Lobby - search for store near you
- Whistle Stop Trains
- Amazon - search for what you want
- JoAnn’s Fabrics - mostly a fabric store, but has a lot of other stuff