MCW Metallic Enamel Issues

[stevieb54]

Im having issues with using MCW paints. Ive tried thinning and using straight from the bottle like MCW recommended. The issue is Im using .5 tip and when I sprayed spoons it pretty much made distinctive 3/8" or so spray lines no matter if I adjusted psi between 15-20, but when I sprayed Alclad primer it flowed beautifully. Does any one have a suggestion of whats wrong? Only reason for the MCW paint is I need this particular color to finish a classic muscle car I'm building. TIA

 

[urumomo]

what is the issue ?

the width of the spray pattern is chiefly governed by the distance from the work and how far back the needle is from the spray tip .

 

[stevieb54]

Thanks for replying. Its hard for me to explain clearly bear with me. In comparison the primer comes out in a fog spray when held in wide open (usually do this for large areas), but when using the metallic enamel you can barely see any paint coming out, it also seams it takes forever to empty the paint reservoir.
In regards to the tip to needle clearance is that adjustable?

 

[stevieb54]

I just realized something after I sent this. When assembling the AB after cleaning or changing tips, I insert needle until its lightly seated, hold it there and tighten nut. Should I maybe try unseating it before tightening?

 

[urumomo]

No , you're setting it up correctly .
The tip distance from the opening is controlled by how far back you pull the trigger .
My point being that air pressure has a minimal affect on the width of the line -- that is chiefly controlled by the distance from the work and how far back you pull the trigger .

Supply pressure and paint viscosity are the 2 elements that impact the flow rate .
Sounds like you need to add more thinner ? ... 25 psi should be the max air necessary for higher viscosity coatings .
What is the thinner you are using and what is the thinner to paint ratio ?

A bigger needle/ tip obviously flows more paint and produces a wider line . , but .5 mm should be fine for that paint .

 

[stevieb54]

This last attempt was at 15 and 20 psi respectively and undiluted. In the past with similar paint I mixed 1:1 sometimes 2:1 but then the gloss seemed to be gone. Ive tried their own reducer too. I use Mr Color 400 leveling thinner.

 

[urumomo]

Using a reducer ( thinner ) with a faster evaporation rate can dull down a gloss paint by not allowing proper film formation .

Try 25 psi with the MCW un-thinned and see what happens . Up to 30 psi max . -- move the airbrush a little farther from the work .

 

[urumomo]

That 400 isn't a good match at all for that enamel :
https://www.zinnfigur.com/securityf...OAO9A1b2tl8_1Z-negx74R_3zCLI8QmiE0J6LmuF09Rhp


use mineral spirits or their thinner for it --- which will be mineral spirits

 

[stevieb54]

Ok i have gallons of that. So should I go 1:1 ratio?

 

[urumomo]

Start out with un-thinned but bump the pressure to 25 psi and see what you get .
Then thin minimally from there -- the less thinner the better ,, you'll need to experiment .

That 400 leveling thinner is a bucket of ketones garnished with a low weight alcohol ( ethanol ) -- much better suited for acrylics or nitrocellulose paints .

 

[stevieb54]

Thanks for your help, I tried a few things and was able to see some better results. This kept me from canning the whole AB process! Heres my results:
@25 psi w/o thinning no better than before.
@25 psi w/ 1/2:1 didnt see much (my AB has a velocity cone on end), I tried removing it and proceeding, things improved somewhat.
@25 psi, now thinned just shy of 1:1 and without the cone on end, I was painting :O).
My results were total coverage, but the finish has orange peel.
Is this something that takes a huge learning curve to eliminate, or can sanding before I clearcoat take care of this?
Anyway thank you again, you restored my confidence.

 

[urumomo]

you restored my confidence.
LOL

Is this something that takes a huge learning curve ?
Not necessarily huge ,
like everything else it just requires some practice / experimentation .

I prefer correcting the paint application issue over sanding out the problem -- although you will need to do that if you have now painted the actual model .
Are you practicing on scrap ? or is this orange peel now on the kit ?

You might be applying too much paint at once ,, or , if not that , Try slightly more thinner and slightly higher air pressure .
go in short steps with the thinner and air pressure increase .
Proper atomization of the paint is necessary to avoid the orange peel .
Avoid heavy coats .
Multiple , lighter coats of paint , with enough dry time between coats .

 

[stevieb54]

Im practicing on scrap spoons. I used different colored primers to find a good baseline for the final color. Still have more spoons.

 

[Littlemarten]

Im practicing on scrap spoons. I used different colored primers to find a good baseline for the final color. Still have more spoons.

Other factors to consider are temperature and humidity of you spraying environment. You want it to be ~70°F, relative humidity 40 to 50%. If you cannot approximate those conditions, you will have to tweak the reducer to paint ratio to compensate.

 

[stevieb54]

Thanks, finding the happy medium is the hard part. Yesterday was about 85*, not sure of humidity. I made some progress with the mineral spirits, but now I wonder if I should try some of the MCW enamel reducer and see if theres any difference?

 

[Littlemarten]

Thanks, finding the happy medium is the hard part. Yesterday was about 85*, not sure of humidity. I made some progress with the mineral spirits, but now I wonder if I should try some of the MCW enamel reducer and see if theres any difference?

urumomo said the MCW reducer was mineral spirits, though it may have other additives (like a retarder, for example) that might make it a better choice than mineral spirits. Mineral spirits is cheap and abundant, so for experimental and learning purposes, I'd go with that. Once you have good results with it, then try the proprietary reducer and see if the results are better or easier to achieve.

 

[stevieb54]

Roger that, Thanks

 

[stevieb54]

Other factors to consider are temperature and humidity of you spraying environment. You want it to be ~70°F, relative humidity 40 to 50%. If you cannot approximate those conditions, you will have to tweak the reducer to paint ratio to compensate.

I just looked up humidity for when I typed this yesterday. It was 67%, today is supposed to be higher. How do you compensate for higher levels?

 

[Littlemarten]

This is where the art of airbrushing comes in. With practice and experience, this becomes almost instinctive, though it can be overwhelming at first. Metallic coatings are the second hardest to master, due to the platy nature of their pigments. (Clear glosses are the hardest, IMHO.)

Generally, increase the reducer slightly. You may have to experiment to find the best increment. Applying thin coats also becomes more critical. With a metallic paint especially, the surface should still look slightly wet, which requires attention to spray volume and distance.

Do you have a spray booth or are you doing this outside? Do you have a water trap in your air line to the airbrush? Water in the air line is often the biggest problem with high humidity.

Temperature is a bigger consideration than humidity (too rapid drying and curing.)

 

[stevieb54]

Im using a paint booth and have an additional inline filter, this has helped. I experimented yesterday on a few spoons I primed previously, the best of three I painted was after I added some more thinner, a lot more gloss shiwed. Lucky I bought 2 bottles of the same color.