Orange peel varnish over decals? (Vallejo acrylic varnish)

[Guest]

I've just had a major problem appear on me that I'm trying to figure out why it happened?
I normally use matt varnish from Vallejo that I'm thinning out with Vallejo airbrush thinner and it works great.
I'm always trying new things to improve my modelling skills and here I'd build my first air plane, and in 1/72 scale too, so there were many firsts here.
Using matt varnish on a plane seemed so wrong so I bought gloss varnish just for this, but the same brand so I didn't have to think about it.

The first layer of varnish I applied after painting it. It went on fine and the results were smooth and blank.

I then applied the decals and let it dry. The next day I decided to put down a new coat of the same gloss varnish, but just over the decals, in preparation for the weathering process so I just did exactly like the previous layer.
I use Tamiya decal softener to fix my decals, just so you have all the parameters, but the decals were bone dry so it shouldn't have affected this?

Anyhow, the varnish went on fine and I expected it to level out as it dried - but the next day I discovered that the varnish I sprayed on the decals were like orange peel and not flat and shiny at all...
There's no chance that the decals were dirty because I had used Tamiya decal softener/fixer and used a q-tip to smooth them out which leaves the decals very clean.

I tried to sand the high spots on the varnish with 1200 grit wet sandpaper which made it better, but not as good as if it'd worked...

What could've caused this? The decal fixer? Humidity? Temperature? (as in colder temperature) Something else?
Clear coating just have to work and not destroy the models or leaving orange peel effect on the surface.

The orange peel effect didn't just happen over the decals. It also happened outside where I'd over sprayed, just to describe it as good as I can.

Is there a good solvent based, quick drying, varnish that's safe to use without it dissolving any layers of paint underneath or are we stuck with acrylic varnishes that doesn't float out and self lever properly?
I think the reason why this happened is down to humidity and colder temperature, but that's just me guessing...

(There's no point taking pictures because I've attempted to use creative weathering to cover the fiasco with limited success.)

What do you think happened? How to avoid it in the future using this brand and type of varnish?

Many thanks in advance!

[Guest]

I gave up on spraying anything Vallejo ages ago but that is just me. I have never had this happen before but it could be a reaction to the decal fixer on the surface even though it was dry. I read somewhere that you should clean off the decal fixer, I only ever use Microsol, with a cotton bud just damp with water or IPA to ensure that it has no residue left over. Having said that, it is not something I do very often. Having no experience of the two products you are using, it is tricky to say.

[Guest]

Alclad's ALC 600 Aqua Gloss. BarryW put me onto this, and it is top stuff. Don't shake it, despite your instincts!! And clean up thoroughly as soon as your done spraying!

[Guest]

I'd guess you're right about the temp/humidity.
A drop in temp causes some really odd things to happen to paint, especially given you've used it already and it went on OK, I truly don't believe the decal fixer will be at fault as I think it would be more localised to the decals.
As fit a good acrylic gloss, the only one I've ever used that came anywhere close to enamel or cellulose was by Fimo, the coloured modelling clay people, the pot I got was from my ex when she had a craft shop and stocked fimo but I guess you'd find it online, unfortunately it's so long since I used it I can't remember if I thinned with ipa or water.
I coated this model with it which was built for a friendas a replica of one he had before.
RGV250Gamma26 by mike michael michaels, on Flickr

[Adrian "Marvel" Reynolds]

These replies are copied from model car forums.

Orange peel is the result of paint drying before it has time to self level. There are a lot of causes that are variants from the "normal". An increase in temperature causes it to dry faster. Spraying from a greater distance makes it arrive at the surface dryer. A slight reduction in the ratio of paint to thinner has the same outcome. Using a different quicker drying (lower temperature) solvent also causes the effect. Once you have identified the culprit, the the solution becomes obvious. As a general rule, I would suggest getting your delivery mechanism(airbrush or can) closer to the model and move faster to prevent drips and runs. Kind of basic, but that is a quick once through.

Orange Peel finish is usually caused by the paint drying too quickly and not having enough time to level out properly. Acrylics are notorious for this because they already dry so fast.

The trick is usually to keep the paint from drying in the air between the airbrush and model and to give it ample time to level out before the carrier evaporates. You can do this in several methods:

1) Thin your paint a little more (although 60/40 sounds fine to me)
2) Spray a little closer to the surface
3) Spray slightly heavier coats
4) Lower your pressure (although the pressure you are using sounds fine to me)
5) Try a different thinner (although with Tamiya gloss paint their thinner is the way to go)
6) Add a couple of drops of acrylic retarder to the mix (although I think Tamiya thinner already has some retarder in it)
7) Keep drafts such as fans from blowing on the paint while it's drying.

Temperature and humidity also have a big effect on paint drying time, but there is usually very little we can do about that.

Having just started to do a number of cars I'm glad its not happened to me just yet, hope you resolve it.

Adrian

[Guest]

Have a go at brewing your own thinner Jens, you can use top quality retarder and flow improver, and drop your pressure if you can, as I'm convinced orange peel is partly to do with pressure, but most of all, a really thin coat is almost unable to orange peel, by default, so maybe try more coats, but lighter? Worth a bash, IMHO.

[Guest]

Thanks for all the suggestions and theories!
I doubt the varnish dried too fast from spraying to far away since this varnish takes up to 48 to dry if you put on a thick coat and that only leaves the Vallejo thinner and the possibility that it didn't mix properly and thus caused it to form droplets on the surface as it dried? This due to colder temperature, and also perhaps humidity?
I'm spraying @ 15-ish PSI so I don't think my pressure is too high, but I'm using a 0.15mm nozzle and needle so I can probably lower the pressure further and see how that works?

I am however going to look for another varnish, a solvent based one - or iso, because I'm fed up with the drying time anyway, and the Vallejo varnish has a tendency to dissolve if I use certain enamel products on it even after it's cured and that's never good...

Alclad's ALC 600 Aqua Gloss sounds interesting! I will look this up!

Yet again, many thanks for the help! Paint and varnishes should just work if you ask me and if they don't, or they have to be used in specific conditions, then they have no place in my toolbox because temperature and humidity shifts rapidly where I live and it's a really old and big house so I can't maintain an even temperature unless I spend a fortune on heating...