discussion Clearing varnish through AB?

[pjgtech]

Another noobie AB question....
How do you know when you have suitably cleaned / flushed through the AB enough when using clear varnish?
Obviously with any sort of pigment/paint, you can see if any paint is left after cleaning/flushing, but not so with anything clear!
I assume its just a matter of making sure you give it a good clean and flush, and then hope for the best? Or is there something else I have not considered?
Cheers

 

[PaulTRose]

What sort of varnish?

I just use loads of airbrush cleaner then water then cleaner a few cycles

 

[pjgtech]

Mostly Tamiya (flat and gloss) and Humbrol (gloss) plus some others...eg: Mig/Ammo Lucky varnish

 

[pjgtech]

As an addendum to this, (see above) I've only used varnish once through my AB, and am about to use it again.
First time I used my 0.3 needle, should I use a larger (eg: 0.5) needle instead for varnish?
I did find that I had to do several coats of varnish first tyime round, presumably cos they are thinner coats?

 

[flyjoe180]

First time I used my 0.3 needle, should I use a larger (eg: 0.5) needle instead for varnish?
I did find that I had to do several coats of varnish first tyime round, presumably cos they are thinner coats?

Your 0.3 needle should be enough Peter, unless you need a larger spray pattern for a large scale kit. Yes, the coats are thinner, but you should be able to apply it in thin layers in one session as you would with paint.

Re cleaning, a generic airbrush cleaner solution should do it. I use Tamiya's airbrush cleaner. If any doubt, spray some lacquer thinner through, it removes everything.

 

[LeytonO]

If you use lacquer thinner it might be a good idea to check the seals afterwards, its quite potent stuff.
I only use acrylic varnish, but find for larger areas a bigger needle size works better for me.

 

[Tim Marlow]

As an addendum to this, (see above) I've only used varnish once through my AB, and am about to use it again.
First time I used my 0.3 needle, should I use a larger (eg: 0.5) needle instead for varnish?
I did find that I had to do several coats of varnish first tyime round, presumably cos they are thinner coats?

Several thin coats are always better than one thick coat

A larger nozzle/needle will give you a wider spray cone for a given position of the trigger, but will also use more air and varnish because the overspray area will be greater. Air use will only be a problem if your compressor can’t keep up, and varnish use is up to you.

Personally, I prefer a 0.3 needle for everything as it gives more control. I use the airbrush more like an air driven brush than a spray gun though, and I know others don’t. Whatever works for you, works, so try it and see,….

As to cleaning, the brush should be easily cleaned by spraying a couple of cupfuls of cleaner through the brush. I would strip, clean, and relubricate the nozzle and needle though so the needle doesn’t stick and the brush is in tip top condition next time you need it.

I have used lacquer thinner and MLT (which is similar) through my Iwatta for many years with absolutely no seal issues, but cheaper brush copies may use inferior quality seals. If you are in doubt a final blow through with water will remove cleaner residuals.