So this just came across my radar on Google AI.
As of 2025, my general practice for modeling is to wash metal and resin models always. Mild soap/detergent and warm water.
I don't wash plastic models as a general rule, be they like fantasy models like Warhammer or military models. Never had a problem with adhesion.
With the advent of 3D printed models, which I began to purchase and paint around 2020-2021, I have never as a general rule washed 3D printed models as they don't come out of a mold, since they don't use a mold process! And therefore don't use mold release agents since there's nothing to be released, etc.
Which begs the question, what exactly would be the reason to wash a 3D printed model before priming?
The AI, along with a number of modeling forums, mention washing RESIN 3D printed models but not washing FILAMENT 3D printed models.
To be honest I never even bothered to find out the difference. All I know is, some 3D printed stuff seems to be sturdier and feels somewhat like toy or styrene plastic when handling it. Others seem more brittle, and thinner parts are sometimes almost as fragile as dry spaghetti strands.
But in either case, I never washed either type, and never had any adhesion issues with primer or paint. In fact, in ten years of priming, I had ONE model that had a true adhesion issue. It was a set of resin historical A frame tens, I believe they were actual resin cast and even after washing, they heavily resisted primer and it fell off without any provocation.
But that was the only instance.
So, the question is, do you wash 3D printed models before priming? And if so, why?
