Decanting and airbrushing Duplicolor Sandable Primer

[jchrisf]

I never had any problems airbrushing craft acyrlics.. it all just went on smooth.  It just isn't durable enough and I never could get a good gloss with it so I have moved to lacquers.  

I decanted some Duplicolor Sandable Primer that I hear so much about here and tried to put on a light, first coat so I wouldn't get any crazing.  It came out like sandpaper (see photo below).  What am I doing wrong?  I shot it with a Paasche H, #5 needle and nozzle at between 25 and 35 psi with the same results.

Edited July 29, 2018 by jchrisf

[BigTallDad]

Looks like too much air pressure and/or too much distance...the paint is drying mid stream.

[Snake45]

Why decant and airbrush it? Just shoot it out of the can. 

[Day 2 Muscle]

48 minutes ago, Snake45 said:

Why decant and airbrush it? Just shoot it out of the can. 

I agree, its pretty thin to start with.

 

 

Robert

[jchrisf]

1 hour ago, Snake45 said:

Why decant and airbrush it? Just shoot it out of the can. 

Two reasons... it has crazed every model I have used it straight out of the can because I get it on to thick I guess and also because this prototype car has lots of fins and tunnels that the paint won't go into from the can.  I need to back the flow down and get it in there.

2 hours ago, BigTallDad said:

Looks like too much air pressure and/or too much distance...the paint is drying mid stream.

That is kinda what I was thinking.. so I should back down the pressure?  I might have to try 15 psi next since it is so thin.

[BigTallDad]

15 psi sounds about right. Practice with that pressure and vary the distance between the airbrush and the part being painted...I'd start with a plastic soda bottle for practice purposes.

[jchrisf]

Thanks Raymond, I will do that.. I'm definitely going to practice on something other than the car body before attempting again, but only because you suggested it.  I didn't even think about a plastic soda bottle.

[BigTallDad]

18 hours ago, jchrisf said:

 I didn't even think about a plastic soda bottle.

Just make sure you perform "normal" preparation (washing, drying, etc.) before spraying.

[peteski]

Plastic soda bottles are made from a different plastic than model kits and will not be a good indicator if the paint will attack polystyrene or ABS (from which most kits are made). Bot if the goal is to verify how the paint covers and its gloss level, a plastic bottle will work well.

[Art Anderson]

4 hours ago, peteski said:

Plastic soda bottles are made from a different plastic than model kits and will not be a good indicator if the paint will attack polystyrene or ABS (from which most kits are made). Bot if the goal is to verify how the paint covers and its gloss level, a plastic bottle will work well.

Yes.  Those blow-molded soda bottles are made from a clear plastic called "PET-G", which is completely different than the polystyrene we know as the material for molding model car kits.

Art

[Art Anderson]

On 7/29/2018 at 4:02 PM, jchrisf said:

Two reasons... it has crazed every model I have used it straight out of the can because I get it on to thick I guess and also because this prototype car has lots of fins and tunnels that the paint won't go into from the can.  I need to back the flow down and get it in there.

That is kinda what I was thinking.. so I should back down the pressure?  I might have to try 15 psi next since it is so thin.

Chris, I have used Duplicolor lacquers for decades now, to paint model car bodies.  Here is what I have discovered, that works for me EVERY time I do it:  First thing, is thinned paint (which in this case is lacquer):  I decant a quantity of the lacquer into my airbrush color jar (in my case, the 3/4 fluid oz jar for my Paasche H airbrush), and then add common lacquer thinner (which I get at Walmart), cap the jar, and gently shake to mix thoroughly.  When I see that the lacquer (be it the Dupicolor primer or my color coat(s) "sheets" down the inside of the clear glass bottle just as 2% milk does on the inside of a glass tumbler, it's thinned well enough.  

Next, I hook up the airbrush to my air line, fire up my compressor, then do a test shot of spray--after which I bleed off air by opening the petcock at the bottom of my moisture trap (the same can be done by stopping down a pressure regulator) until I get just a very soft spray.  After adjusting the spray pattern to what I want, I then airbrush this very thinned lacquer (first primer, then color) up close, about an inch or so off the surface of the model car body or parts in question.

I have come to call my method "TSC" for "Thin, Soft and Close".   Now with the first passes on a body shell with this lacquer  & thinner mix,  you will notice a VERY fine "crazing" of the plastic surface, more like a light "frosting" of the surface.  However, this is VERY minor, in my experience, and by the third pass or so around and over a body shell, it goes away completely, while giving me a surface that still shows all that cool, fine raised detail we pay good money for.

Once I am satisfied with the primer surface, and i've given it a bit of a polish with say, a 5000 grit piece of emery cloth, and washed away all residues with toothbrush and good old Dial Soap (scraps of which I always seem to have at my hand sink--rinsed thoroughly (!), I then blow-dry the body shell and any associated separate panels with my airbrush hose, and then repeat the process with the color coats.

TSC has worked like a charm for me, since the very early 1970's, when I learned to do it by experimentation.  

Art

[Ace-Garageguy]

4 hours ago, peteski said:

Plastic soda bottles are made from a different plastic than model kits and will not be a good indicator if the paint will attack polystyrene or ABS (from which most kits are made). Bot if the goal is to verify how the paint covers and its gloss level, a plastic bottle will work well.

I started recommending people scuff, primer and practice spraying small soda bottles years ago, after seeing how many folks got good results painting spoons, but ended up with horrible orange peel, grainy dry-spray, or runs when they tried to transition to shooting model car bodies.

Painting a spoon is nothing like painting a model, but boy, did I catch a lot of flack for bucking the "expert" advice.

Not everyone has a stash of junk bodies to practice on, and a small soda bottle is large enough to develop the skills and coordination required to overlap paint passes correctly to keep a "wet edge" while turning the subject being painted, and to learn to hold that fine line between running and flowing out into a nice glossy surface.

 

Edited July 31, 2018 by Ace-Garageguy

[Joe Handley]

Look into these.

https://www.dipyourcar.com/collections/speed-shapes

I picked up a few to play with, they're cheap and appear to be vacuum formed sheet styrene

[peteski]

3 minutes ago, Joe Handley said:

Look into these.

https://www.dipyourcar.com/collections/speed-shapes

I picked up a few to play with, they're cheap and appear to be vacuum formed sheet styrene

Those styrene shapes are a great idea, but unless you are going for the "hippopotamus skin" effect. that paint job is horrible!  Good thing it is on a test piece.

[Joe Handley]

25 minutes ago, peteski said:

Those styrene shapes are a great idea, but unless you are going for the "hippopotamus skin" effect. that paint job is horrible!  Good thing it is on a test piece.

Yeah, that was an experiment with embossing powder that didn't pan out, got something else to try, but I'l do that on a spoon first. I do have a friend that uses those embossing powders for carpet though!

[peteski]

Yeah, from what I see embossing powder works well for scale carpeting.

[jchrisf]

11 hours ago, Art Anderson said:

Chris, I have used Duplicolor lacquers for decades now, to paint model car bodies.  Here is what I have discovered, that works for me EVERY time I do it:  First thing, is thinned paint (which in this case is lacquer):  I decant a quantity of the lacquer into my airbrush color jar (in my case, the 3/4 fluid oz jar for my Paasche H airbrush), and then add common lacquer thinner (which I get at Walmart), cap the jar, and gently shake to mix thoroughly.  When I see that the lacquer (be it the Dupicolor primer or my color coat(s) "sheets" down the inside of the clear glass bottle just as 2% milk does on the inside of a glass tumbler, it's thinned well enough.  

Next, I hook up the airbrush to my air line, fire up my compressor, then do a test shot of spray--after which I bleed off air by opening the petcock at the bottom of my moisture trap (the same can be done by stopping down a pressure regulator) until I get just a very soft spray.  After adjusting the spray pattern to what I want, I then airbrush this very thinned lacquer (first primer, then color) up close, about an inch or so off the surface of the model car body or parts in question.

I have come to call my method "TSC" for "Thin, Soft and Close".   Now with the first passes on a body shell with this lacquer  & thinner mix,  you will notice a VERY fine "crazing" of the plastic surface, more like a light "frosting" of the surface.  However, this is VERY minor, in my experience, and by the third pass or so around and over a body shell, it goes away completely, while giving me a surface that still shows all that cool, fine raised detail we pay good money for.

Once I am satisfied with the primer surface, and i've given it a bit of a polish with say, a 5000 grit piece of emery cloth, and washed away all residues with toothbrush and good old Dial Soap (scraps of which I always seem to have at my hand sink--rinsed thoroughly (!), I then blow-dry the body shell and any associated separate panels with my airbrush hose, and then repeat the process with the color coats.

TSC has worked like a charm for me, since the very early 1970's, when I learned to do it by experimentation.  

Art

Art.. what pressure do you spray at?

[Art Anderson]

1 hour ago, jchrisf said:

Art.. what pressure do you spray at?

I have no idea as to the actual air pressure, as I do not have a pressure  guage  (never ever felt the need for one, still don't(.  I merely open up the petcock on the bottom of my moisture trap (It's the old-fashioned Binks water trap from 55 yrs ago, has a threaded "drain valve" on the bottom ) until no spray, then adjust it to lowest pressure spraying by closing it.   I've been using the technique I described,  for at least 50 years now, and it's never failed me.

Art

Edited August 1, 2018 by Art Anderson

[jchrisf]

Thanks Art.. that is what I thought you were saying.  I'm going to reduce mine the next time and see how it goes... I'll try it closer too.  I was probably around three inches away when I shot the primer on the pic I posted.