Brushing acrylics over gloss

[Vlad]

I've recently decided it's much easier and more pleasant to brush on gloss coats than to use spray cans. I use a pot of Humbrol 35 acrylic thinned with water and a nice big brush. Most of my painting is also done in the same way but I've run into a problem. I've started using various Xtracrylix paints to fill out my range where Humbrol won't do, which is fine in itself and I like them.

 

The problem is, they dry to such a gloss finish they more or less reject further paint application, which is a big problem for the overall gloss coat. When thinned with water (and to extent even unthinned) the Humbrol paint visibly shrinks away off the surface of the dried Xtracrylix, leaving a "raindrop" effect that's quite annoying to get rid off. It's possible but requires constantly brushing the affected area while it's drying, which can lead to other issues like streaks.

 

My question is, what can I use to improve the flow and adhesion of water thinned acrylics on highly gloss surfaces? If it wasn't obvious already, I'm fond of my brush only, no smell, water based work area so bear that in mind before recommending solvent based flow enhancers or something like that. I want this simple and clean, if that's possible. Maybe a different type of brush or technique? Some surface preparation to take the edge of the Xtracrylix?

 

Thanks!

[LotusArenco]

You probably need something to reduce the surface tension to stop it beading up.

Try a tiny drop of washing up liquid? Or better still dishwasher detergent, as I think it has ‘anti-foam’ properties.

Failing that, something like Liquitex ‘Flow Aid’ (not smelly or solvent based).

Mart

[Vlad]

Thanks, I will try the washing up liquid next time and see if (or how much) it bubbles. I have also used Liquitex spray cans for varnish in the past and am generally impressed with their quality and low smell plus non-aggressive medium. In the long term I might get myself a pot of that stuff, since some Xtracrylix can also be a bit awkward to brush. Do you use it instead of the water to thin or add a bit to a water thinned mix?

[LotusArenco]

47 minutes ago, Vlad said:

Do you use it instead of the water to thin or add a bit to a water thinned mix?

You add the flow aid to water (distilled or DI water if you want to be fancy), then use that water mix to thin your acrylics. It’s a bit pricy (£7/£8), but a pot will last you years.

https://liquitex.com/flowaid/

 

Mart

[sapperastro]

This is why I try not to use gloss acrylic paint that will be painted over (with more acrylic), or, if necessary, add a little Tamiya flat base to the paint mix before applying. Enamels don't really have this problem, but Acrylics dislike a super smooth finish as it has no 'bumps' to adhere to. You could try adding a little xtracrylic flat varnish (if this exists?) to the paint mix too, that may work, especially if you don't like the idea of mixing paint brand products.

Edited January 8, 2018 by sapperastro

[Vlad]

It seems Xtracrylix do have a flat varnish, which I did not expect because everything they do is gloss. However from doing some quick reading it doesn't seem to come out very matt. Xtracrylix seems to go down fine over itself, and to be honest I don't want to kill the gloss finish as it helps with decals.

 

Haven't had a chance to try the washing up liquid trick yet because I finished the project that prompted this question but another is close to that stage.

 

If I'm not happy with that, what I'll do is just buy Xtracrylix varnish instead of Humbrol to use for the final "seal everything in and make it look consistent" coat. Probably the satin or gloss kind as I like my kits shiny and I've had bad experiences with other flat coats in the past (Humbrol again) drying milky white.

[Guest]

Their flat varnish can be VERY flat, it's just needs to be really well shook up.  I killed the finish on a Lancaster with it a few years back.

[LotusArenco]

Xtracrylix flat varnish is my usual choice for a nice flat finish, but I airbrush it so have no idea how it brush paints.

Winsor&Newton Galeria matt varnish gets some good write ups and is perhaps worth a google image search, you’ll see lots of modellers and figure painters using the stuff. Liquitex matte varnish is most probably very similar (they are made in the same factory).

 

Mart

[Murdo]

Winsor & Newton Galeria matt varnish is superb stuff!

[Uncle Pete]

Related question... I've just sprayed acrylic varnish (Humbrol rattle can) on a model (never varnished one before) and it fogged the clear parts.  It also seems to have caused the enamel (Humbrol) paint to blister.  I gave it two weeks curing time before hitting it with the varnish figuring that would be enough.  I'm not too fussed since the plane didn't build that well and so I'm using it for decal practice, never having used the setting solutions before.  Have I done something egregiously wrong or have I encountered a common problem?  I've had a look at tutorials on youtube but not had much luck finding my specific problem.  Should the clear parts be masked off before varnishing?  Should I switch to stamp-collecting?

[fewr9fkr9595]

16 minutes ago, Uncle Pete said:

Should the clear parts be masked off before varnishing?

Answered your own question there mate 👍🏿

[Vlad]

Well, I have to say the washing up liquid in the mix worked a treat. The Humbrol 35 clear basically applied itself and self-leveled even on Xtracrylix gloss. A bit of foaming (it was funny on the exhaust stacks) but I brushed it out other isolated bubbles melted away themselves. I was tempted to try the Xtracrylix varnish and I still might, but for now am very happy with this! Thanks!

 

@Uncle Pete I have in one case sprayed varnish over unmasked clear without consequence but this was a Liquitex can and they are very benign. Even so it thickens it and therefore isn't great. Better just keep the mask. These days I leave the canopy mask on for the duration of the project, peeling it off is basically my "unveiling" routine, absolute last thing I do before I hang a plane.

 

Humbrol rattle can varnish in particular seems to have some nasty strong stuff in it, it's not fully compatible even with their own brand brush paints. I had a bit of cracking on the first project I tried it and ditched the can. Probably if you practice laying it on really thin it won't do that but it isn't worth the grey hairs in my opinion. As I said before, brush painting varnish is standard for me now.

Edited January 15, 2018 by Vlad