Airbrushing Humbrol varnishes - help needed please

[Gern]

Hi guys. Like the title says, I want to airbrush both gloss and matt Humbrol varnishes and need some help. I have an H&S Ultra brush with a 0.4 nozzle so:

What pressure should I spray at?
What should I use to clean my A/B when I've finished?

I've noticed a white substance has settled to the bottom of my bottle of matt. I assume I have to mix this back into the varnish, but I've got a little niggle at the back of my mind saying you need to be careful that you don't get any bubbles in the varnish when you mix it. Any ideas guys?

 

[Ian M]

i think you are over thinking it Dave. I look at it as if varnish was just paint with no colour!
I thin it and spray it as if it was anyway. I'm probably wrong though.

As for the white substance in the bottom of the bottle, yes that would be the matting agent. You will need to stir it up very VERY well. (I buggered a rather nice tank by spraying a Humbrol mat that had not been shaken enough. one of the best gloss finishes I have done)!
I dont think the bubbles are a problem. Most Airbrushes have a built in bubble filter that removes all bubbles before they get to the mixer, thus stopping them from blocking the nozzle. I think if they start giving you problems you may need a new bubble filter.

 

[Gern]

i think you are over thinking it Dave. I look at it as if varnish was just paint with no colour!

Sounds fair enough Ian. What cleaner do you use?

Most Airbrushes have a built in bubble filter that removes all bubbles before they get to the mixer, thus stopping them from blocking the nozzle. I think if they start giving you problems you may need a new bubble filter.

Huh!!??

 

[rtfoe]

Sounds fair enough Ian. What cleaner do you use?

Huh!!??

Dave, first answer from Ian is obvious about treating varnish like any other enamel paint. You mix it with enamel thinners to the same consistency as the paint you spray with. As enamel is petroleum based you will need a cellulose thinner to clean the airbrush receptacle and flush the paint out.
On the second answer he's just pulling your leg. Since bubbles rise to the top, the gravity feed will draw the bubbless bottom liquid to the needle tip where the force of the air will lift the paint off the tip out of the nozzle.

Cheers,
Richard

 

[Tim Marlow]

Where you need to minimise bubbles in varnish is for hand painting…..they can sit in crevices and give you craters in the finish.

 

[Gern]

Dave, first answer from Ian is obvious about treating varnish like any other enamel paint. You mix it with enamel thinners to the same consistency as the paint you spray with. As enamel is petroleum based you will need a cellulose thinner to clean the airbrush receptacle and flush the paint out.
On the second answer he's just pulling your leg. Since bubbles rise to the top, the gravity feed will draw the bubbless bottom liquid to the needle tip where the force of the air will lift the paint off the tip out of the nozzle.

Cheers,
Richard

Humbrol varnish is water based, not enamel. My go to cleaners are methylated spirits for Vallejo paints and IPA for Tamiya paints and Stynylrez primers. Just wondering if either of these would be OK or do I need something different?

 

[rtfoe]

Humbrol varnish is water based, not enamel. My go to cleaners are methylated spirits for Vallejo paints and IPA for Tamiya paints and Stynylrez primers. Just wondering if either of these would be OK or do I need something different?

Oh dear, the last time I used Humbrol varnish it was enamel based. So you're using the 'new' aqueous range of Humbrols which are supposed to be acrylics. Haven't tried these so can't comment except that generally most acrylics would work with the cleaners you mentioned.
It's just me but I would just test a drop with each cleaner and see the results for myself and that's been the way since I first started in this hobby...fearless and like the crew of the USS Enterprise, go where no one has been before.
I still use hardware industrial thinners to flush my airbrush and don't wait till the paint has hardened or cured then you're in trouble.

Cheers,
Richard

 

[Tim Marlow]

Sorry Dave, I thought you were talking about the tinlet stuff, not the big bottles. I use the bottled gloss occasionally and just use the same cleaning regime as I do for Vallejo acrylics. Basically rinse through with water to remove the residual wet varnish, clean through with Vallejo airbrush cleaner (other makes are available) to get out any dried stuff, then rinse through with water. Meths or IPA will work just as well, but cellulose thinners is less flammable if you are just going to spray it through.