Filtering

Maybe none of this directly addresses your issue but it's my reply till someone familiar with those specific products chimes in.  I wouldn't say that Vallejo's own washes shouldn't work over their own paints but if in trying that I ran into what you have run into, the indication to me would prompt me to put down a clear lacquer barrier coat between them. That said, I haven't used their washes over their paints . A very thin clear lacquer coat will usually do it in situations I like it that I've been in.

It's funny, I'll do a craft paint wash or oil stain wash over acrylics. But the craft paint is one where I may not intend to wipe it off but more dap at it and soak up the excess, this a deal where you don't let it dry before wiping. Same for artist acrylics made into a wash... But artist oils made to a wash over acrylic can be washed up with odorless mineral spirits. I mostly make my washes at any rate.

I have only used Model Colour paints and not there clears or washes. If the latter 2 are both acrylic, then that is your problem. The wash need to be a different type of paint to the layer its being aplied to. So oils/enamels over acrylic or acrylic over lacquer/enamels.

I mainly use Vallejo paints, but I don't use either their varnishes or their washes.  However, I wouldn't expect any problems when these are used over their own paints.  All I can suggest is allowing a longer drying time - a lesson I have just learned the hard way about Vallejo primer!  I thought 24 hours would be enough, but evidently not.  So 12 hours may not be enough for the varnish.  Also, how long are you leaving the paint before varnishing it?  

FWIW, I use Pledge floor polish* as a protective coat over any paint, followed by washes made from oil paint & white spirit.  I have yet to have any problems with damage to either the Pledge or the paint underneath.  You can pick up a set of oil paints very cheaply at a branch of The Works & a bottle of white spirit at Wilko's, if you're interested.

I hope this helps.

      Hutch.

*"Pledge multi-surface polish"

Bish is right. It should be an enamel/oil wash. You can use a enamel/lacquer clear coat to seal the paint before the wash. the acrylic wash is re activating the paint and clear coat.

Weathering is generally enamel over acrylic and acrylic over enamel. Mild solvent paints generally do not harm acrylic and acrylic do not harm solvents.

Thank you Bish. Much appreciated. This will help   Vallejo never reference any other products than their own for all stages - which is all acrylic.  

Thank you Hutch.  Now properly stocked up

Thank you for your help Oldermodelguy. I hadn't considered lacquer as an option. Much appreciated

Thank you Tojo 72. I saw my mistake after  I had posted   I did mean filter. I have tried applying an enamel clear coat over the acrylic base colours which seals things nicely but a filter layer over the top of this just coalesces - like paint on glass!   I'll try an enamel wash without the clear coat and apply as you suggest. I think I'm tying myself in knots - a filter is not generally an issue for folk!

I use Flory washes over enamel gloss paints and i get the same reaction. I just keep applying it until it holds. Have you tried adding a drop of washing up liquid to the acrylic filter to help break the surface tension.

I much prefer enamel and oil washes as i find them easier to work with and you have more time to work on them. My only issue is that as i use enamel paints i have to ensure a good acrylic clear coat to protect the paint.

Thank you Bish    I'll try the washing up liquid tip. I've got a big sheet of acrylic to test out what works. I'll let you know

Always satin varnish coat the Model Air paint first and let it cure for at least two days (48 hrs) before applying a Vallejo Model Wash filter. If you want to use Model Wash as a filter, add 3 drops of distilled water to one drop Model Wash...it will be transparent as a filter. I personally use oil or enamel based filters over my water base acrylics (Vallejo, Hataka, AK) but I always satin coat the paint first.

Thank you High Desert.  I have tested this on an old model.  Extended cure time IS the answer- at least with Vallejo products.   It's useful to have this option for their filters and washes as I have stocked up in a big way