Vallejo primers?

Vallejo Thinner

I've stopped using Vallejo primer.

1. It frequently clogged my ABs even when thinned with Vallejo Thinner.

2. It is NOT sandable.

Yup - Tamiya thinner don't play nice with Vallejo. Stick with Vallejo thinner brand to Vallejo paint.

I use good ole DupliColor primer or Rustoleum primer in the rattle cans.  I've never had any problems!

Tamiya Fine or Mr Surfacer 1200 in the rattlecans for me.

VJ appear do two primers, 'normal' (!) in small bottles.

And the Polyurethane in multi-sized bottles, I like them for the the range of colours they have, even using the US OD undercoat as 'topcoat',  but not the grey for any purpose!

You are right, It doesn't sand well, if you still need fettling, you should use Tamiya, Mr Color, Halford's or similar, & only .

My 'soup de jour' is VJ cut with about 25%-50% old style Future/Kleer, which helps a lot with workability/sandability.

VJ ahem 'recommend' a higher pressure for spraying, which helps.

It's more of a sealer than a primer.  There's a guy on youtube hitting vallejo primer with hairspray minutes after spraying and he claimed to be able to sand it like normal primer in about 10 minutes.  I found it easier to just use something else.

The reason why you can't sand Vallejo primer is that, when cured, it turns into a rubber-like coat.  You cannot sand rubber.  Having used Vallejo primer, I see no reason to use it when other primers do an infinitely better job.

Ditto on the rubber-like coat.  It's the only item in the Vallejo line that I don't use.  Still rely on Dupli-Color sandable grey for all priming.

Jim