I recently painted a part of a model kit with Tamiya X-1 Black. I primed the surface with Tamiya Surface Primer, with 2 light coats and a 3rd “medium” coat. I let it dry for 10 minutes, then airbrushed Gloss Black onto the primed part. I gave it 3 light coats. I then let it dry and cure for 3 days.’
But here is the problem, even after that much time, the paint scratches easily. I put a decent amount of pressure onto the surface with my fingernail and the paint scratches off, revealing the plastic/primer. Is that normal?
Some notes: I airbrushed app. 3 inches away, with 16 PSI of pressure. I dilluted it with thinner, approximately 1:1 ratio thinner to paint, until the spray is even (not runnny or splattering). I let it dry for 7 minutes in between.
Some questions:
1: After applying surface primer, how long should I wait before airbrushing color?
2: Is it normal?
3: If it is normal, then what do you do to make the paint more scratch resistant? Keep in mind I did not add Paint Retarder, or clear coated it.
I thin mine with lacquer thinner, it seems to be pretty tough, now I don’t try to scratch it with my finger nail, why would I do that? But with normal handling it holds up well
Sounds like the primer wasn’t dry and the topcoat kind of sealed it and kept it from drying.
10 minutes would only give it time to flash off and lose the wet look. Try letting any paint coats dry at least overnight. I would say you’re tending to rush to fast.
I haven’t had any trouble with X-1 over stynylrez. It may be more fragile than enamel that’s dried 4 days to a weak but for average handling it’s been fine. I haven’t exactly taxed it’s durability though, I mean I pick things up with the pads of my fingers not my fingernails. I’ll do delberate scratch tests with fingernails but haven’t done that with X-1 ( I’ve done a series of these on primed and unprimed prescription bottles with various paints, also sanded unsanded).I thin X paints with either lacquer thinner or denatured alcohol. The primer is dehydrated for 10-30 minutes, then air dry for 2 hours to overnight. I often prime then shoot color the next day. I often scuff the primer with a 3200 or 3500 grit soft pad mesh ( those 2x2 sanding pads) or 000 or 0000 steel wool. Not always but often do. It gives the top coat something to grip. Same with the model parts.
Another vote for giving the Tamiya Surface Primer no less than 2 hours of drying time before painting. I did a lot of experimentation with this on some spare parts from a completed build and I found that anything less than 2 hours gave me problems of one kind or another. My test for paint adhesion never involved deliberately trying to scratch it with anything though. I always used Dymo tape, burnished a piece of that onto the painted surface, and then ripped the tape off. Once I got a technique down where the Dymo tape didn’t lift any of the paint, that’s what I stuck with…and it always took a minimum of 2 hours for primer drying time. That being said, I have always found Tamiya paint to not be very durable, which is one of many reasons I’m using mostly MRP paint now. When that stuff cures (takes about an hour for their standard acrylic lacquers), its almost as if the part you painted was actually molded in that color. Very resistant to scuffing and scratching.
Exactly. Or just do something else non modeling and come back to it later.
But I tend to brush paint my engines unless they’re all aluminum colored. And I do that at the half assembled point of the engine. So other stuff can be in primer or paint as I assemble an engine to where it needs paint. Brush that, now it’s drying and I go to other parts, maybe to start assembly. Primer dry, glue up sub assemblies etc. All in stages. Right now I have 4 kits all in different stages. I just put another one away to work on a different one. The only thing done to the one away was a wash on certain chrome parts. And so it goes. I have two all painted, everything,finish coat and all waiting assembly.
I’m not sure that there is much in modeling that benefits from haste other than unsticking your fingers from CA glue.
I tend to work in sub-assemblies within the same project and don’t necessarily follow the instructions in exact order. Of course, you want to look ahead to make sure you don’t box yourself in, but things like missiles can be painted separately while the fuselage is drying. Sometimes the most effective medicine is a “tincture of time”.