Hey all,

I sprayed Vallejo's grey primer yesterday with good results and noticed that a few seams need to be taken care of. Today, I tried sanding the primer down a bit so I could use some putty for the seams but noticed that I could not sand the primer smooth (as I'm usually able to do with other primers). Instead of being able to feather the coat of primer for a smooth feel, the primer seems to come out in small chunks/pieces. I'm I doing something wrong or is there a method to getting Vallejo to sand smoothly once applied.

Thanks much!

Rob

I have never tried to sand, but it sounds like it may not of had enough time to dry.

Thanks for the feedback, Kevin. Seems to me that a full 24 hours would be enough to at least handle the part. Looking at the sanding marks closely, unlike lacquer primers which actually bite into the plastic, the Vallejo primer seems to just be a layer that sits there on top of the plastic part.

Don't get me wrong, if I didn't have to sand it I would have been really happy as the primer came out really smooth and self-leveled pretty well. What annoys me is that a primer also supposed to help with spotting mistakes on the surfaces (i.e. seams, scratches, etc) so these can be rectified before the base coat. Being that I can't seem to feather/sand the primer smooth to correct the imperfections, I'm afraid I'll be able to notice where these 'chips' came off the part either when I reapply the primer or when I shoot the base coat.

Thinking about stripping the parts I sprayed so far but don't know what would be useful for that. Any hints?

Rob

Rob

Sounds like stripping might be your only option. The other issue is it may have been put on thick. And yes, lacquer based primers will bite into the plastic, Vallejo won't.

Good luck with it.

Kevin

Rob, I'm not going to be much help for you this time around since I don't use primer to find flaws.

For your next one you may want to try what I do...
check seams and any areas where you may think its rough with Tamiya liquid primer or Gunze surfacer applied with a brush, and smooth them down with IPA. This way when you do lay down your primer, it'll be just that, a base coat. I started really concentrating on this when I started sending out assembled kits with absolutely no paint on them, for friends to paint, so I wanted to make sure they were good to go straight to the paint booth 'right out of the box'. I don't handle lacquer fumes too well, but by using a brush the odor is minimal, and the all my airbrushing can be done in acrylics.

Thanks much for the feedback, gents. I agree James...it's important to check for flaws before applying the primer coat. In all honesty, I was able to get away with other primers like Mr. Surfacer and Tamiya out of the can but I guess, with Vallejo, it's a whole different ball game.

And just for the record,I do exactly what you do and make sure I test my seams with Mr. Surfacer 500. When I did this on my current project, I did not notice any issues. Vallejo's primer though showed the outline of the piece in question pretty well so I have to fix that somehow.

Some good news, however. After I sanded the primer a little more with progressively finer grits, I decided to shoot the primer again. Thankfully, besides really small bumps that are hard to see, I can say that all other scratch marks were covered successfully.

This being my very first tome shooting the primer, I'm pretty impressed overall.

Rob

Hi Rob,

If you have used one of the new polyurethane primers, it is the devil to sand. It appears Vallejo formulated this range to resist scuffing and abrasion check the product description on their website.

Hi William,

You're correct, it's indeed the devil to sand. I'm used to primers that can be smooth out and feathered, especially being that I do used them to check for flaws. I guess I just can't use Vallejo's for anything other than an undercoat for paint.

Rob

Hello all,

I know this is an old thread, but I'd just like to verify that the Vallejo surface primers CAN be sanded and handles without scratching (even with a finger nail, pressing down). I'm new to air brushing and when I first got the air brush I primed a junk model (plastic washed, as always) and tried sanding the primer, and it's rock solid. Just give it more time than enamel primers. Hope this helps.