hi im having a problem painting my latest effort using my airbrush ,the paint is just running on the plastic and looks terrible ,it as if the paint and plastic are reacting with each other or like there is oil on the surface of the model (which there isnt) ,im new to airbrushing and this is only the second thing ive sprayed the first a tamiya 1/48 halftrack i did yesterday turned out brilliant no problem at all ,im using tamiya acryilcs thinned with their thinners .
the model im having trouble with is a revell salamander and im using tamiya RLM grey ,ive tried using different thinesses of paint different pressures on the brush and it just turns out the same ,could it be that the model needs a primer coat ?or am i doing something way wrong ?like i say im new to this air brush lark so any advice would be welcome

cheers

There could be a few things causing your troubles. The paint could be TOO thin, or too much air pressure combined with a too-thin paint. The plastic could need cleaning.

How thin have you made the paint, and what air pressure are you spraying?

Generally your paint should be the consistency of milk.....but what % milk I've asked....I usually go for a skim milk, or maybe 1% consistency. I like a lower air pressure ( 15 psi )....I believe most guys run between 15-20 psi. I believe the thinner the paint, the lower the pressure you sould use.

You mentioned there isn't oil on the surface of the model, but are you sure? Have you cleaned it? I recently had a problem with paint pooling on the model. A wipedown with Isopropyl alchohol fixed it. Even if you've washed the parts before assembly, your skin oils can accumulate during the build.

Hi Phil,

It sounds like there is an oily surface on the model as Greg mentioned. Try a wash in water and detergent to get rid of it before spraying.

Did you prime the kit before applying the paint? Some of us use an aerosol acrylic primer as this shows up any slight faults (badly filled seams etc) and allows them to be fixed but it also acts as a key for the airbrushed paint to get it to adhere to the surface.

An alternative method of priming is (using the airbrush) to dust light coats of the Tamiya acrylic onto the surface and then use only the air from your airbrush to dry it before going back with a heavier coat, again this will allow the paint to adhere to the surface.

hi thanks for your replies ,
to answer your questions,
i thinned the paint approx 3:1(milky consistency) spraying at 20 psi at first ending up more like 1:1 at 10psi 3rd try same results with the paint ,i cleaned the paint off with the only thing i had at the time -industrial hand wipes ,now these will clean up a dirty car engine so any oil or grease on the surface would have been cleaned off ,2nd try slightly better this time as some of the paint did dry ok while the rest looked very glossy ,seemed to separate and wouldn't dry ,3rd try worst still, thing is i cant understand why the other model painted so good at the same psi with the same type of paint and same ratio mix ,i think im gonna try a primer ,would plasticote plastics primer be any good ?as ive got a can in the shed

cheers

I have done quite a bit of trial and error with tamiya paints and found 20 psi at about 6 inches distance to model with an ambient temp of at least 60 degrees F , my paint ratio is 70/30 as "lampie" has suggested and primer is not an option I use a Paasche millenium with a compressor meant for model or other hobby airbrushing, I like useing floquil enamel primer as it seems to adhere better however tamiya acrylic primer is pretty good too, good luck.

Phil,

What are you using for a moisture trap? Condensation could be contributing to your problem especially if the humidity increased since your first build.

Brian

hi
im using a normal filter /moisture trap/regulator/inline oiler thing(with out oil obviously),and the temperature had dropped since the day before (actually it did snow at one point ) and this had crossed my mind as a possible cause maybe i need some sort of heater in the outhouse

temp of the room is crucial, minimum temp is 60 f? not quite sure have to look that up, here in boise the outside temps get as low as 0 and heating an entire garage is not going to happen, so I am going to build a paint booth with a fan venting fumes to the outside otherwise this will be a seasonal hobby.....not! an outhouse here in Idaho is a small rustic outdoor toilet building...is that where you paint?

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yes i know what you yanks use an outhouse for here its a brick built building that in days gone by would have been used for storing the coal for the fire ,now its my mini workshop ,so its looking like the cold weather was the cause of the problem ,i'll warm up the place and try again

cheers

This might sound like a silly question, but are you using the correct thinner for Tamiya acrylics? Remember that they also have an enamel line (not sure if they are available in the UK).

Tamiya acrylic thinner is X-20A and enamel thinner is X-20.

Using a compatible thinner, it's almost impossible to over-thin Tamiya acrylics. I often use up to 80% thinners with no adhesion problems.

well ive found the problem , temperature it was just too cold ,i bought a small electric heater warmed up the shed and resprayed the model with perfect results

thanks for your help guys

I use only tamiya acrylic thinner with corresponding paint, their enamel paint is not available here, on one of these threads someone said that tamiya thinner has a paint retardant that seems to produce better results, some guys use a drop of dish wash liquid to achieve same results personally I trust tamiya thinner.

see my photos, very interesting two story Idaho territory outhouse at silver city not to far form where I live.