Hello!

Whenever I get water on my painjobs, it leaves permanent stains. Does this happen to you as well?

I have made experiments where I apply clean tap water with a brush to unvarnished, gloss varnished and matt varnished surfaces. I always get these annoying little marks.

I use Vallejo acrylic colours and varnishes and I always let the paintjob dry for at least 24 hours before I start experimenting.

Does anyone know why this is happening and if it's normal?

I sometimes get water stains , after I wash a model before I paint it, not after. As I use sink water.
I guess one could use Distilled water, which I use for thinning water based paints,as no minerals in it R/O might work good to.

Cheers

Thanks for your reply!

I have actually experimented with distilled water but it also stains the paintjob. It leaves transluscent spots where the water has touched the model.

If anyone feels up to it, I would be very happy if someone would try and put a small drop of water on a paintjob to see if it leaves a mark!

Yes, it does on acrylic finishes, especially if they are satin or matte. I would recommend using clear coats to protect the paint job. As side note: Micro Sol and Micro Set also stain unprotected finishes. Another occurrence: if you use a brush to apply water on the model (let say before applying decals), never use a brush you were painting or applying pigments with. Even if looks clean, it may be not (acrylic pigments are very resilient once dry). All above are related to my past errors.

I hope it helps.
Gabriel

Thank you so much for your reply! It's great to hear that this is an innate property of acrylic paints and not the result of me doing something wrong with the paints.

The stains did occur even on a gloss varnished surface, but I had not put so much varnish on the model that it actually became glossy. Maybe I should be a bit more generous with the gloss varnish in the future!

It's not just acrylics. I painted almost exclusive with enamels and lacquers for decades and I'd get water spots on them too. To me it seems the problem is the finish. It's difficult to clean them off of flat and satin but much easier to clean off from gloss. I used a q-tip lightly moistened with IPA and using a twisting motion scrubbed/blotted the spots. Hard water was the worst, but even distilled was a pain. Don't know what affect that will have on acrylics as I've haven't been using them as long and haven't had that problem. It even got spots on Testors dullcoat but they would fade after cleaning and another application of dullcoat.

Nice answer, I do not get them ,but then again I do not use acrylic washes, only oil, but do get them some times, after a sink wash, some will not go a way strange that. Unless I use a good hit of Lacquer spray. I have to make note of which company, I think Dragon are the worse.

Enjoy.

It's a paint finish problem, akin to decal "silvering". It often occurs because microscopically, flat and semi-flat finishes have a porous "sandy" appearance which reduces reflectivity. The chemical makeup of water then leaves a residue within this grainy surface. There are four ways to remove it that I've learned work pretty well-- two of which have been mentioned already-- 1) using IPA on a Q-tip, or 2) coating it with a flat or gloss sealer, which really just fills in the spaces in the grainy surface. The other two ways I've used are to 3) "wick" excess moisture away with a paper towel, then use the highest air pressure setting on your airbrush/compressor to blow away any moisture, and finally, #4)--gently using a solvent remover opposite that of the paint-- i.e.; Acrylic thinnner on enamel finishes, or enamel thinner on Acrylic finishes. There is a fifth method, which is to use fine steel wool (oooo gauge or higher) to lightly buff the finish out-- but this usually requires a topcoat which could have been done with #2 above. I've found that Distilled water doesn't make much difference, as it picks up chemicals from the paint finish anyway. I've heard of folks using ionized water, but it's seems expensive to use for what's easily solved with other methods. In Decal silvering, air is trapped in the porous finish, and the decal film seals it in-- that's why modelers use a gloss coat under their decals.
VR, Russ

Wow, thank you so much for your replies! Finally I lay this issue to rest!

You have saved me a lot of time and anxiety by clearing this up for me!

A good way to prevent that is to protect the paint with Future before using anything thinned with or containing water. Just make sure it's cured first.