"Adhesion Promoter for Plastics?" Topic

I read a comment recently on another website (another hobby), that plastic models/figures don't need primer, but they do need to be sprayed with adhesion promoter.

I'm not familiar with adhesion promoter. Anyone here using it?

Never heard about it…

Never heard if it and never used it. And I've been building plastic kits since the 1960s.

I suspect it may depend upon the type of plastic(s) being used.

TAP Plastics is an excellent source for all things plastic, including glues, etc..

I'd call them if you need assistance.

You will find it at automotive stores. I think I got mine at
Pep Boys. It is by Dupli-Color. On the can it says "ideal
for plastic, vinyl,& chrome".

According to Eastman chemical:
"An adhesion promoter is used as an additive or as a primer to promote adhesion of coatings, inks, or adhesives to the substrate of interest. An adhesion promoter usually has an affinity for the substrate and the applied coating, ink, or adhesive. Without the adhesion promoter, the properties of the applied coating may not be sufficient to meet the performance requirements needed for the end product such as a painted automotive plastic surface. In automotive coatings, the term adhesion promoter refers to the primer, which achieves adhesion of the subsequent paint layer to TPO substrate. This adhesion promoter is usually comprised of chlorinated polyolefin (CPO) as the active adhesion-promoting component, other resins, and pigment. "

So, to me, it sounds like a part of a typical primer. In automotive (and machine) terms "Primer" also has a rust inhibitor in it. In wood prep a "primer" would also fill and seal the grain. Clearly these are not needed for models. But it is more of a matter of the term having slightly different meanings depending on the area of interest you are coming from.

Rust-Oleum makes a plastic primer. It preps the plastic to make a tooth for the paint to adhere to, that surface itself strongly bonded to the plastic.

Like using flat (matte for our European friends) which is preferable over gloss as a primer. A flat (insert your favorite color for priming here) leaves a microscopic rough finish which refracts light (giving it that "dull" look). Those microscopic ridges provides a "tooth" for the color you next apply to grab hold of. Acrylics (think liquid plastic here) fills in between those ridges and valleys. Conversely, using a gloss as an undercoat does not allow for a good bond because the resultant finish (gloss) is smooth- a desired property to reflect light and thus makes the color look shiny.

The Rust-Oleum product does not etch it's way into the plastic to make the bond, rather, it's more akin to a spray adhesive which dries leaving another surface that will allow your acrylic paint to better bond than mere flat enamels do. (Ever see the enamel spray enamel rub off on your fingers before it gets coated with an acrylic color? This stuff seems to be like spraying plastic over plastic. BTW, their product stock number is 209460 in a 12 oz.spray can.

I tried a can on a whim and will use it on my Hat, Revell, Zevzda, Airfix, etc. figures when I move back to my 1/72nd scale figure projects.

Hope this helps.

v/r
Tom