discussion Airbrush Paint Finish

[ChrisP]

Hi All. I am a recent returnee to scale modelling. Given the size of my fingers 1/24 is the smallest I can go! I am retired but the average 14 year old would tell me a lot about modelling, the thing being is that I have totally re-fallen in love with it even though I am still pretty crap at it. So here (finally) is my problem. I have an Iwata Neo AB. I am using Vallejo Surface Primer, 74.601 Grey. I wash the model in a light detergent mix and then rub the surface down to remove any shine. I spray the primer on, let it go off for at least 24hrs and then carefully check it to make sure it is all smooth. Recently when I then spray the paint on (Vallejo) and sometimes even if I try and paint on, it comes out looking like oil on water !(best description I can come up with). My 'set up' is in the shed (very large) unless there is snow when I moved a lot of it indoors (wife not happy!). So, can anyone tell me what I am doing wrong? Is temperature anything to do with it? Or am I just an idiot, which would not surprise me!! Over to you experts

 

[Tim Marlow]

Sounds like surface contamination. Are you rinsing off the detergent Chris? If not, it’s probably worth it. After that I wouldn’t rub down again because you may be making the surface dirty again and it is migrating through the primer back to the surface. Just let the primer air dry then spray your top coat.

 

[Guest]

Sounds to me like you're doing everything right!

Caveat - I am NOT an expert.

When you say 'oil on water', do you mean the paint is pooling, as if it's separating? And I understand that this is happening when you are applying the paint on top of primer, is that right? Are you thinning the paint at all?

 

[stillp]

Sounds to me as if you're putting the paint on too thickly. Try a very light 'dust' coat.
Pete

 

[BarryW]

Humidity is a real issue with water based paints, regardless.

Make sure the paint is thoroughly shaken/mixed and spray in very light coats at between 20-25 psi or lower, not higher. You could also have a final clean up by wiping with ipa.

 

[David Lovell]

Hi Chris as with some of the others on here I've never washed a kit plastic or resin let alone rubbed the shine off ,saying that I know a lot of the chaps do so unless you've left a soapy residue I cant see a problem there , plus as you've described the primer seems fine .Sounds stupid but have you mixed the paint throughly prior to thinning and have you mixed paint and thinners properly. Its not as if your in the shed working with temps hovering around zero the only thing I will ask how well do you store the paints is there a chance they've got frosted?

 

[Jim R]

Hi Chris
Welcome to the forum.

.... it comes out looking like oil on water

Do you man the paint beads up on the primer or do you mean that somehow the paint looks like the rainbow effect seen in puddles when oil floats on the water?
If the paint is beading up then the primer surface is not compatable or the paint is over thinned with water. If you are thinning with water you are diluting the "structure" of the paint - try using Vallejo thinner. As the guys have said light coats and work at a lower pressure. The surface tension which causes liquids to bead up can be reduced with a drop of wetting agent in the paint. A TINY drop of washing up liquid can work.
Just my random thoughts :rolling:
Don't give up - you'll sort it.
Jim

 

[ChrisP]

Sounds to me like you're doing everything right!

Caveat - I am NOT an expert.

When you say 'oil on water', do you mean the paint is pooling, as if it's separating? And I understand that this is happening when you are applying the paint on top of primer, is that right? Are you thinning the paint at all?

Thanks for answering. Yep, got it in one. I do thin the paint a little but I am very careful about that (I think)

 

[ChrisP]

Hi Chris
Welcome to the forum.

Do you man the paint beads up on the primer or do you mean that somehow the paint looks like the rainbow effect seen in puddles when oil floats on the water?
If the paint is beading up then the primer surface is not compatable or the paint is over thinned with water. If you are thinning with water you are diluting the "structure" of the paint - try using Vallejo thinner. As the guys have said light coats and work at a lower pressure. The surface tension which causes liquids to bead up can be reduced with a drop of wetting agent in the paint. A TINY drop of washing up liquid can work.
Just my random thoughts :rolling:
Don't give up - you'll sort it.
Jim

Thanks for answering. I use Vallejo thinners, but only a couple of drops. Might try and use even less.

 

[ChrisP]

Hi Chris as with some of the others on here I've never washed a kit plastic or resin let alone rubbed the shine off ,saying that I know a lot of the chaps do so unless you've left a soapy residue I cant see a problem there , plus as you've described the primer seems fine .Sounds stupid but have you mixed the paint throughly prior to thinning and have you mixed paint and thinners properly. Its not as if your in the shed working with temps hovering around zero the only thing I will ask how well do you store the paints is there a chance they've got frosted?

Thanks for answering. I am wondering about the temperature in the shed at the moment. That may have something to do with it.

 

[Guest]

Ok. I suspect then that the pressure might be too high and you're putting too much paint down too quickly.

Consider lowering the pressure to below 20psi so you are delivering the paint in a more controlled way and try experimenting with the thinning ratio. I use 15psi and thin 50/50, but you'll need to figure out what's best for you.
Also try to lay a thin coat first and build it up. Don't try to get all the paint on in one pass.

 

[Tim Marlow]

Which Vallejo paint are you using? Model air or model colour? Vallejo do an airbrush thinner as well as a straight thinner.....I assume the airbrush thinner has more flow aid in it to help with airbrush work.

 

[ChrisP]

Sounds to me like you're doing everything right!

Caveat - I am NOT an expert.

When you say 'oil on water', do you mean the paint is pooling, as if it's separating? And I understand that this is happening when you are applying the paint on top of primer, is that right? Are you thinning the paint at all?

Thanks for answering. I thin the paint with a couple of drops of Vallejo thinner. Usually 2 - 3 drops. Will try and reduce that.

 

[ChrisP]

Ok. I suspect then that the pressure might be too high and you're putting too much paint down too quickly.

Consider lowering the pressure to below 20psi so you are delivering the paint in a more controlled way and try experimenting with the thinning ratio. I use 15psi and thin 50/50, but you'll need to figure out what's best for you.
Also try to lay a thin coat first and build it up. Don't try to get all the paint on in one pass.

Thanks for the answer. I will try this and report back - eventually.

 

[ChrisP]

Which Vallejo paint are you using? Model air or model colour? Vallejo do an airbrush thinner as well as a straight thinner.....I assume the airbrush thinner has more flow aid in it to help with airbrush work.

I haven't really looked at the paint other than the colour matches that I want. I will have a look.

 

[Guest]

Which Vallejo paint are you using? Model air or model colour?

This is a great question.

Are the lids white or black?

 

[Guest]

When you say pooling like oil on water straight away I think like Tim surface contamination.

 

[Steven000]

I use only alcohol for degreasing the model before airbrushing, might be a better option for you to try than the soap-mixture.

If you can post a picture of the problem, the guys here might be able to help you even better.

Cheers
Stevn

 

[ChrisP]

Sorry about not answering you all. Suddenly got busy plus I wanted to try some of your suggestions out and see what worked. Temperature seems to play a big part. I am in my workshop and I have a portable heater but clearly it doesn't get as warm as indoors. During the summer it is sweltering and I cannot recall the problem. Not sure about the detergent because I tried a test piece, thoroughly washed and rinsed it and still had a bit of a problem. I think I have come across one problem/solution. Vallejo paints need a LOT of shaking before use and I mean a lot. Whether that is a temperature thing or what I don't know. Nearly got RSI shaking the last bottle lol. Within the next couple of days I will be using Zero paints for the first time so will make sure they are ok by temperature and I am also aware that they are lacquer paints. Steven000 I am going to try your idea with alcohol (hic), I have some 99% ISA so will try that. I will report back and if anyone has experience and advice re Zero paints I would welcome them.

 

[NonnyM]

I had a similar problem with a new airbrush and other than the advice above, I can only add that I found it very useful to practice on used yogurt pots

Probably not suitable for recycling afterwards though?

Rgds