Nick Farrow Posted March 9, 2009 Share Posted March 9, 2009 Hi, I am just attempting to paint my gws foamy p40 with my son's humbrol air brush - and have gone back to hand painting! I dont really know what I am doing, but i'm just wondering if its me or the air brush! I have diluted the acrylic paint to about 50% and have 2 new cans of propellant. I get about 15 seconds of spray time before the nozzle starts to drip on the plane, if I keep wiping it, I get alittle longer before the force of the air seems to tail and spraying stops. If I leave it 10 mins or so it seems fine, I dont think the propellent is dying, not quite sure why this is happening. For a plane every 2 years or so, I'm not buying decent spray kit and I'm not after a top notch finish for a £30 foamy, but something that does justice would be good and hand painting only looks good @20+ meters! Any advice weclome. Thanks nick Quote Link to comment Share on other sites More sharing options...
winchweight Posted March 9, 2009 Share Posted March 9, 2009 I get a good finish with a brush, but use a good quality brush, sable or similar. Quote Link to comment Share on other sites More sharing options...
Gemma Jane Posted March 9, 2009 Share Posted March 9, 2009 If the nozzle is 'dripping on the plane' you are far to close. What is happening I would guess is that the acrylic paint is drying on the nozzle OR the paint is not thinned enough- it is one reason why I prefer to spray enamels. If it is drying and you have water handy, try running water through the brush - and try again, if the paint starts to flow again, this is the problem. Most paints spray best if the consistency is like milk, perhaps you need a little more thinning if you have a lot of build up on the nozzle. I hate air cans, practically useless to be honest, if you are going to spray at all you need a small compressor at least. Quote Link to comment Share on other sites More sharing options...
Erfolg Posted March 9, 2009 Share Posted March 9, 2009 Nick A problem with cans of propellant is that the pressure drops with time. From your physics lessons years ago you will remember that the state of a gas is dependant on pressure and temperature. To get from a liquid to a gas requires energy. Hence as the canister empties the pressure drops, because it needs that energy to get to a gaseous state. The ANSWER put the can base in a pan of hot water and it will take in energy from that source. The pressure will remain constant for longer. With regard to the dripping etc. A lot of what others have said is true, witha major proviso, there needs to be an supply of air at an adequate pressure and volume. So it could be that most of your problems are due to lack of compressed air, rather than mixing issues. I would guess that because your pressure is low, you are getting, closer and closer to your model. Just to compensate. I normally find that the paint is pretty much dry as it hits the surface. But I have copious amounts of air from a compressor. I am not sure how faraway I am from my surface, but I think for fine work it could be about6-9 inches, for a whole area ala Badger type about 10". Erfolg Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted March 9, 2009 Share Posted March 9, 2009 Nick what paints are you using? Many Acrylics can be used straight from the pot and don't need thinning. I spray those little Tamiya pots straight. Quote Link to comment Share on other sites More sharing options...
Ernie Posted March 9, 2009 Share Posted March 9, 2009 Hi Nick, I use a simple single action Badger airbrush. It is perfectly adequate for our type of use. A sophisticated double action job is really only needed by graphic artists. However, you do need to practice. Use a water based (acrylic) paint. It should be about the consistency of milk . The brush should be around a foot from the surface, and it must keep moving. The cans of air are always a problem, they run out at a critical time, and when the shops are closed. Are you getting enough pressure? You can make a perfectly adequate compressor from an old fridge motor (details available if you wish) It is possible to brush on a good finish, but it is much more difficult, and you need a top quality brush. Finally watch for the dreaded overspray ernie Quote Link to comment Share on other sites More sharing options...
Bruce Richards Posted March 9, 2009 Share Posted March 9, 2009 Is that full fat milk, skimmed or semi-skimmed Quote Link to comment Share on other sites More sharing options...
Erfolg Posted March 9, 2009 Share Posted March 9, 2009 With regards to compressors. It is possible to buy a small piston compressor with tank, these days cheaply. There disadvantage is noise. But this is very intermittant for the amount of use a modeller uses it. My own cost £20 from B&Q, a managers special offer. I have used a diaphragm compressor, hardly quiter than the piston compressor. Plus you need a trap, ususally. The pressure is somwhat limited. My own went in the bin, once I got a piston jobby, as they are totally inferior in performance. I have used the cans, were expensive, limited life, pressure is an issue if spraying a lot. Put kettle on luv. I have even used car tyres pumped up to 50 psi. Total waste of thime after about a minute. As for the airbrush, for flat spraying a badger is so adequate, if not superior to a double action job. Badger single action airbrushes are designed for largish area, flat spraying. I must agree that most acylics i use these days are the correct consistency for spraying. I have used "Windsor & Newton Acrylics" from tubes thinned with water, but then i have fixed the result with "Artists Varnish" Other than art work, where a particular colour is required, I cannot be bothered. A lot of art work still use, paint brushes and pens. The airbrush is to provide a flat or vignetted effect in particular. Although art work on cars and bikes does appear to be all done with airbrushing. It may amuse you to know that you can buy a spatter nozzle for many airbrushes. For that spattered effect. Mottled effects are possibly best achieved by use of a near dry sponge, as some German 2 WW aircraft. Erfolg Quote Link to comment Share on other sites More sharing options...
Kelly Posted March 9, 2009 Share Posted March 9, 2009 I sprayed my GWS 190 all over with foam friendly silver paint from a spray can, then brush painted with sky blue emulsion paint , and ordinary acrylics. Quote Link to comment Share on other sites More sharing options...
Erfolg Posted March 10, 2009 Share Posted March 10, 2009 I think the use of images is very useful, so hear are my own This is a similar model to the previous contributer a TA 152H The following is a picture of the some of the inks, Acylics and paints and airbrushes I have used. Yet it is the badger that has done all of the ones shown using just thinned Humbrol. The inks are best when an arty or very quick paint job is required. Erfolg Quote Link to comment Share on other sites More sharing options...
Nick Farrow Posted March 10, 2009 Author Share Posted March 10, 2009 Hi, Thanks for all of the useful comments, pics and advice. I used the Tamiya acrylic pots thinned! But it seems they dont need it (that would be semi skimmed then so thats good to know. It looks like to do a decent brush job you do need a compressor/tank. In the mean time the idea of blatting the surface with a base colour (matt emulsion?) and then doing the arty bits with acrylic pots and a decent brush would seem the way to go. Now I'm half thinking of using the exhausted propellent can as a 'tank' and attaching the piston car pump by adding a schrader valve (ok its not going to be that safe)............. Thank again. nick Quote Link to comment Share on other sites More sharing options...
Erfolg Posted March 10, 2009 Share Posted March 10, 2009 Nick Please do not do this. I am very sure you are wasting your time. You will not get the volume of compressed air in the can that is useful. Remember what ever the gas that goes into a cannister these days, it was cooled and pressurised to turn into a liquid. The second reason, is that it will not be safe, it is essentially a thin walled , uncoded pressure vessel that you propose. Enough energy to do some real harm. I personally would buy another can, and keep ypur eyes open for a cheap compressor. They do come up. Ohh invest in a kettle and a pan to warm the cannister up, or just borrow from the kitchen. As an aside I am anti the safety culture. I believe in accessing risk, and then doing what is commensurate with the risk to benefit. This proposal is very negative in benefit and high in risk Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted March 10, 2009 Share Posted March 10, 2009 In one of the 1983 RCMEs they reported on the jennican, an alloy container with removable cap, schrader valve and spray head. It acts like a rechargeable aerosol; it also has a 90 psi safety valve. Google it and you'll find they're still available for about £20. Quote Link to comment Share on other sites More sharing options...
Ernie Posted March 10, 2009 Share Posted March 10, 2009 Hi Guys, It's not so difficult to make a compressor, from scrap . Old fridge motors are easy to find. If you connect the airbrush direct to the outgoing lead for the gas , you will have a sort of workable source of air. but it does pulse a bit, and there can be lubrication issues. Much better to find an air tank, maybe an old fire extinguisher, or a calor gas bottle, etc. Use a bit of common sense, remembering it's under pressure. You might want to add a water trap, and a pressure gauge, so that the layout is Fridge motor..water trap..air tank..pressure gauge and regulator..But, do be careful, compressed air can be dangerous. Now, here come the health and safety brigade. BOOM ernie Quote Link to comment Share on other sites More sharing options...
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