Gloss Varnish is sometimes Tacky or lightly Sticky to the touch

[Splurch]

I've been encountering some problems in a search for a new varnish. Mostly on leftover sprues that I've painted up just to test varnish. I started painting off and on again last year and eventually decided I had enough of spray sealers and wanted to go brush on/airbrush. I haven't moved on to the airbrush stage yet as I've been having problems actually finding a varnish. I've got two that seem to work well for the gloss coat, Liquitex High Gloss Varnish and Vallejo Gloss Varnish. Occasionally a coat will stay very slightly tacky after it has dried (multiple days). Sometimes (but very rarely) it dries just fine.

 

At first I thought it might be my wash, as I'm following instructions to make Lester Bursley's washes. After some testing I did realize that with too much brushing the ink can reactivate, but doesn't always cause the tacky problem. I give the paint multiple days to dry before sealing. I've tried very thin layers, thick layers, watered down layers, multiple layers etc and all have the same, occasional problem. The gloss coat is just occasionally slightly tacky. Now this isn't super tacky, just to the point that when I press down with a finger it will stick to it for a second or two then fall off (longer when it happens with bones, due to their lightness). Even the ones that don't end up tacky exhibit this, but fall off almost instantly. Also, after they have cured, if I leave a piece touching another piece for a few days they will stick to each other slightly. I never had this problem with sprays. I haven't been able to find any problem like this online. Is this something inherent in the formula of gloss brush ons that sprays don't exhibit? Is it likely to stop if I airbrush it on?

 

Putting a satin/matt coat (also liquitex/vallejo brush on) over the gloss does reduce this stickyness drastically, especially in the ones that are particularly bad. It only completely eliminates it in some of them.

Edited March 20, 2014 by Splurch

[Pingo]

This is something that I as a fine artist have been struggling with for years. It's one of the reasons most of my (non-mini) painting is in media other than acrylic.

 

That said, I have worked out a few things. Painting with thin coats and giving lots of drying time seems to help. Acrylics may dry to the touch much faster than oils, but they still need time to fully dry. Even the thinnest of coats aren't really chemically dry until after a full day.

 

Don't use too much medium. Early on I wanted to really protect my paintings so I put on too-thick coats of gloss medium. But they tended to stay tacky to the touch.

 

It does not take a lot of gloss medium to protect acrylic paint. A single thinned-down coat does a pretty good job.

 

Not all gloss media are the same, by the way, and some brands and types are better than others. For example, Golden makes a medium called GAC 200 which increases film hardness and reduces tack which dries pretty unsticky. It's unsuitable for flexible surfaces because it can crack if flexed too much, but I found it great for painting fiberglass and now that I think about it, it might be worth a go on metal as well. You're not supposed to use it alone like a varnish, though, but mix it with paint. So it may not solve th sealer problem.

 

Recently after some experimentation, I found that a thin coat of Golden Self Leveling Clear Gel, well thinned-down and allowed to dry, followed by a thin coat of Golden Soft Gel (Matte), also well thinned down with water (and after it dries, if there are still glossy spots add one more layer), served well to get a protected but reasonably matte finished mini.

 

More experimentation is clearly required.

[Splurch]

It's definitely not a drying thing as some of the test pieces I've left a week between painting/sealing etc. So it's somewhat normal for the gloss to be minorly sticky? I've been trying a lot of different varnishes as well, I've actually found Liquitex Satin to be the best to kill shine for a mini to be used (currently testing Vallejo's Satin as well). The Liquitex Satin isn't all that flat, but it is a far cry from gloss and more importantly doesn't change its sheen all that much with handling. Vallejo and Golden both make a matte that is absolutely flat after being applied, but after use they almost becomes glossy in sheen. Good if I wanted to protect a show mini, but just not useful for something that will see play.

 

I may check out the Golden medium you suggested. The paint itself isn't having any tack issues but I have been trying to find a way to make a harder surface (at least for non bones minis). My old mini's were sealed with games workshop spray sealer, which I have to say is the hardest stuff I have encountered so far (can't even get the paint off my old stuff with a fingernail) and I just haven't been able to find anything that comes close to that durability. I'd honestly still be using it if it didn't randomly decide to frost every so often and just destroy hours of work. Think there would be any issues with putting a drop of GAC 200 into the brush on varnish?

 

Definitely for more experimentation. I've been trying many different sealers for months now trying to find out something I'm satisfied with. I've now got a decent number of mini's that are painted and just sitting there unprotected waiting for me to sort out the varnish issues ;)

[smokingwreckage]

I have encountered this, but not often enough to have proper advice. If I did have advice it would be along the lines of "set it aside for a week and see what happens". I have found many things, from super glue to primer, can sometimes require much. MUCH longer to cure properly than what it says on the bottle.

 

So really, I'm just chiming in with "yes it happens" and as far as the culprit, I'd blame the coat that is sticky, not anything under it.

[Pingo]

On the Golden GAC information page they talk about adding GAC 200 to other gloss mediums to reduce tackiness, so it looks like treating it as an additive is fine.

 

In fact, it looks like a mix could be up to 75% GAC 200 without too much trouble, if I read that right.

 

(They also say on that page at GAC 700 can stay sticky, which I have also experienced. I have a test patch of GAC 700 that's 21 years old and it is still a little tacky to the touch.)

[Splurch]

Reading up on their site they recommend using their mediums as a isolation coat between the paint and varnish at most as the medium's aren't designed to be a top coat and won't protect as effectively. As the paint itself isn't having a tacky problem do you think using it as an isolation layer is likely to help?

[Pingo]

I didn't see mention of using GAC 200 as an isolation coat.

 

You know, looking at that page, you might want to try GAC 500. They say it's "the hardest acrylic polymer within the product line that is still pliable enough to be used on flexible supports" with "increased mar resistance and decreased dry film tack." It's also recommended for airbrush-based isolation coats.

 

That sounds like it's close to what's called for for the special needs of minis painting.

[Splurch]

It's on their Gel & Medium Review page where they discuss the difference between varnishes and medium/gel. They do mention GAC 500 specifically there for being particularly suited as an isolation coat.

Edited March 21, 2014 by Splurch