Long lasting paint

[GrandpaPhil]

If I hypothetically wanted to build a model that would be made of plastic, primarily, and I wanted it to last 50 years, what sort of paint would I use, assuming that it would be stored and displayed in a mostly climate controlled acrylic case?

[Darius359au]

I dont know about 50 years but I've got plastic models over 30 that haven't had any paint issues ,I use hobby acrylics like tamiya ,AK ,Mig etc!

Acrylics also have a pretty benign chemistry as well with usually doesn't react with paints under or over them.

 

Richard

[popeye2sea]

My plastic build is going on 45 years. I use acrylics; Tamiya, Model Master, Vallejo, etc. I have never had to repaint anything.

 

Regards,

 

Henry

[Bob Cleek]

The inherent ability of any artistic artifact to simply last is a question any artist or craftsperson who values their time eventually spends some time researching. No doubt there are those who can attest to their possessing plastic models that have lasted "over fifty years," but it would appear from the professional preservationists' literature that those items are flukes. Styrene plastics as we know them today have only been in routine production since the post-WWII period when the war-surplus polystyrene manufacturing plants were converted from their prior wartime production purposes. It was a short time thereafter than the term "plastic" became synonymous with "inferior" and "short-lived." Very roughly speaking, polystyrene plastic as an engineering material has a "shelf-life" of around twenty-five years. I don't know how old you are, but a lot of us "of a certain age" can attest with 20-20 hindsight that twenty-five years is a surprisingly short period of time!  

 

Regardless of how well "climate controlled" your acrylic case may be, you might want to reconsider an "acrylic case." If you want a maximum lifespan, you won't be using plain old "Plexiglass." Archival acrylic vitrine sheet display cases are custom fabricated (often using proprietary UV-curing adhesives) and are as much as four or five times the cost of a "clear acrylic" and for that you get a lifespan of ten to twenty-five years. Glass, while heavier and susceptible to impact breakage, is a lot less expensive and lasts virtually forever. This "cheat sheet" used by professional curators sets forth comparative archival strengths and weaknesses of various materials used in conservation and display of historic and artistic artifacts: Selecting Materials for Storage and Display | Conservation Center for Art & Historic Artifacts (ccaha.org)

 

Most any paint is pretty tough stuff. As long as the pigments are high quality and not prone to fading, most all of the binders in use today, once they cure or polymerize, aren't going anywhere. The archival problems arise with the substrates upon which the paint is applied. They've made a lot of improvements in styrene plastics over the last half century or more since I was building plastic models in the late fifties and early sixties, but no matter how you cut it, plastic is polymerizing material that has a "half-life" as it were. Modern "polymerization inhibitors" can slow the process down, but they haven't found a way to stop it, as far as I know. The literature" suggests that if conserved under optimum conditions (which is a rather tricky thing to do) polystyrene plastic material can be expected to last as long as fifty or even sixty years, but this assumes proper conservation practices. There is a fair amount of information on the subject online. Under "average conditions," they say it's good for around ten years, although improper storage can accelerate deterioration to a "surprisingly short length of time." 

 

Paints and other coatings applied to plastic can negatively affect the longevity of the plastic through chemical interactions and this danger has to be assessed on a case-by-case basis. The general rule of thumb for plastics is that "If you can smell it, it will deteriorate." (Or, more accurately, "If you can smell it, it is deteriorating.") Many plastics and adhesive materials will release acidic gasses as they age, and these can wreak havoc with the lifespan of a model. Heat and UV light will usually accelerate a plastic's degradation. 

 

Unlike metal and wooden ship models, nobody expects a plastic ship model kit to last much longer than about fifty years at best. While everybody's own mileage will probably differ, I never could see the point of putting in the time to do a good job of rigging a complicated plastic square-rigger model that I knew was certain not to last any longer than that. 

 

These MSW articles lay out the basic considerations for maximizing the archival quality of a ship model:

 

Nautical Research Guild - Article - Ephemeral Materials in Ship Models (thenrg.org)

 

Nautical Research Guild - Article - Specifications for Construction of Exhibition Models of U.S. Naval Vessels (thenrg.org)

Edited March 15 by Bob Cleek