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[pugwash]

I have just treated myself to a badger 200 airbrush - and thought I would have a practise morning -
I as yet dont have a compressor - thought I would start with the compressed air cannisters.
I spraycanned primed an old piece of melamine faced board last night and then started today.
Thinned the humbrol enamel 1:1 screwed on the bottle and off I went - I thought the paint
looked rather watery but I persevered for a bit then noticed the airpressure was dropping  so
I shook the can and it carried on for a bit then the same thing happened but this time the airpressure
came up when I shook the can but the paint seemed to be frozen in the airbrush and the front bit(tip?)
was covered in ice
any suggestions please  and what could I be doing wrong

Paintless Pugwash aka gormless Geoff

[essex2visuvesi]

put the air canister in a bowl of warm to hot water ... it helps but its a far from perfect solution.  better off getting a cheap compressor.  I have heard of people using the poundland car tyre inflators with reasonable success.

[pugwash]

thanks essex2v - I used to have the same problem with my gas blow torch when it had been standing
in a cold shed in winter  - warm water or bringing it into the house did the trick- but you dont expect it
to happen when the cen heating is on

[essex2visuvesi]

For some reason as the air is used, the can temperature drops.  Im sure someone can give a more scientific explanation

Also keep a very close eye on the amount of propellant left in the can..  Theres nothing worse than the thing running out as it stutters and makes a mess of your model

[Dueller]

To turn the liquid propellant into a gas it has to be heated, this is usually done by the surrounding air. The liquid uses the ambient heat but in doing so reduces the temp around the can which causes the ice to appear on the can. The cure is listed in the above replies.

If you had ice on the nozzle of the airbrush, this is probably because when you shook the can you allowed unvapourised (liquid) propellant to enter the pick up tube in the can ans so travel to the airbrush when the above reaction took place and froze the end of the airbrush nozzle

[pugwash]

Thanks for the suggestions - a bowl of warm water it will be until a new compressor arrives

Pugwash

[tobyker]

Boyle's law I think - compress a gas and it heats up (bicycle pump) -  expand a gas through a venturi and it gets colder - think Carburettor icing - any water vapour nearby freezes. Cure is carb heating (Kwacker GT550) or  bowl of hot water. It's amazing how long Kawasaki said it wasn't their problem until suddenly we all got a recall!

[pugwash]

SHMBO says I should have remembered boyle's law from school - I can't even
remember which school I went to it was so long ago. Ah yes it was  somewhere in Leicester.
 Re the watery paint - does humbrol need to be diluted 1:1 or would 60:40 or even less
be more appropriate

Pugwash

[westcoaster]

You'll find that different paints (gloss/satin/matt) have differing consistencies. My own view is that thinning 1:1 makes thing just too watery. I read somewhere that you should aim for a "thickness" like milk. So, depending on how thick your paint is to start with, thin until you get a mixture which only just drips from your screwdriver when you stir it. If it all runs off - its too thin. That's what works for me.
The plastic pipettes you can get at your model shop are ideal for adding your thinner gradually. Stick with it, you'll be spraying evenly soon!!

[knoby]

Hi, there's no exact answer to the thinners question, there are many factors to consider. Firstly different colours of paint will have slightly different viscosities & some will 'thin out' quicker that others. Different air brushes will perform better with different thickness of paint, air temperature & air pressure at the gun will all have effects on the performance, as will the size of the piece thats being painted.

That said there are some ball park figures to start with. Personally when using humbrol I start with 60-40 paint to thinners, but always try out on a test piece & experiment with various amounts of thinners. The more you use it , the more you get the feel for it.

The most useful tip I was ever given is, clean the air brush out throughly, & then clean it out thoroughly again. The tinyest piece of dirt will have a major effect on the airbrush & its much easier to clean wet paint out than it is to clean dry paint out.

Cheers Glenn

[pugwash]

Thanks Knoby and Westcoaster seems like it will be just like the rest of my model boating - trial and error.
Hopefully not too many errors

Pugwash