Polished Metal - rough black primer

[AdriaN (MLT)]

Guys i need some advice,

I am about the paint an aircraft alclad polished metal and i know how perfect and smooth the black primer must be for the perfect finish.

I sprayed on the acrylic gloss black and i got an orange peel finish. it looks like black sand paper. This im sure will prevent the finish from turning into a polished look.

My plan is to sand the black with a fine grit, but i would like to know...
1) what grades of micro mesh should i use to smoothen it out?

2) after sanding the black, should i spray on another layer of black, then the alclad? or can i spray the alclad right after sanding?

[Alan P]

I've just had this exact problem

I have rectified it by sanding back with micromesh (started with 3200 up to 6000) and then brushing Klear over it. I probably should have tried respraying the black then, but instead I did Alclad over the Klear. It kind of worked but left the grain of the orange peel still.

[pacificmustang]

Adrian, the grade of micro mesh is not as important as ensuring you end up with a smooth finish free of any imperfections or scratch marks. If you have to go right through the grades of mesh to ensure this, so be it. As your finish sounds quite rough, without seeing it, I would start with 3200 and work your way up. Provided you end up with a smooth finish, it should not be necessary to respray unless you have bare plastic. These will need to be touched up. Thin your paint more, maybe drop the pressure a bit and spray thin coats

HTH

Bruce

[ICMF]

I am about the paint an aircraft alclad polished metal and i know how perfect and smooth the black primer must be for the perfect finish.

I sprayed on the acrylic gloss black

Question: what Alclad shade/s will you be using?

Alclad makes two completely different kinds of paint, with different chemistry and different properties.

The 'regular' Alclad shades are metallic, but not 'mirror-like', and are designed to be applied over a smooth (not glossy) acrylic lacquer primer, such as Mr. Surfacer, Tamiya's Spray Primer, Alclad's Grey/White/Black Microfiller Primers or similar auto primers. The primer mostly acts as a barrier between the (hot) Alclad paint and the (meltable) plastic underneath, to avoid melting or crazing. It doesn't have to be glossy, and it doesn't have to be black.

The 'high shine' Alclad shades are more 'mirror-like' and reflective - chrome, polished aluminium, etc - and are designed to be applied over a glossy, enamel base coat. Alclad recommend their 'Gloss Black Base', 'Clear Base' or a gloss hobby enamel. The reason is, the high shine paints don't bite to the base coat; they simply add a reflective metallic layer on top. The higher the gloss, the more reflective it will be, but the longer cure time of enamels means the slightly tacky surface will promote adhesion.

In other words, if you're using one of the 15 or so 'regular' Alclad paints, your base coat doesn't have to be black, and it doesn't have to be glossy. Just smooth. If you are using one of the 6 'high shine' Alclad paints, your base coat needs to be glossy, should be black, but should also be enamel, not acrylic.

http://alclad2.com/how-to/

[AdriaN (MLT)]

I've just had this exact problem

I have rectified it by sanding back with micromesh (started with 3200 up to 6000) and then brushing Klear over it. I probably should have tried respraying the black then, but instead I did Alclad over the Klear. It kind of worked but left the grain of the orange peel still.

well... FIVE coatings before alclad LOL

[AdriaN (MLT)]

Question: what Alclad shade/s will you be using?

Alclad makes two completely different kinds of paint, with different chemistry and different properties.

The 'regular' Alclad shades are metallic, but not 'mirror-like', and are designed to be applied over a smooth (not glossy) acrylic lacquer primer, such as Mr. Surfacer, Tamiya's Spray Primer, Alclad's Grey/White/Black Microfiller Primers or similar auto primers. The primer mostly acts as a barrier between the (hot) Alclad paint and the (meltable) plastic underneath, to avoid melting or crazing. It doesn't have to be glossy, and it doesn't have to be black.

The 'high shine' Alclad shades are more 'mirror-like' and reflective - chrome, polished aluminium, etc - and are designed to be applied over a glossy, enamel base coat. Alclad recommend their 'Gloss Black Base', 'Clear Base' or a gloss hobby enamel. The reason is, the high shine paints don't bite to the base coat; they simply add a reflective metallic layer on top. The higher the gloss, the more reflective it will be, but the longer cure time of enamels means the slightly tacky surface will promote adhesion.

In other words, if you're using one of the 15 or so 'regular' Alclad paints, your base coat doesn't have to be black, and it doesn't have to be glossy. Just smooth. If you are using one of the 6 'high shine' Alclad paints, your base coat needs to be glossy, should be black, but should also be enamel, not acrylic.

http://alclad2.com/how-to/

Thank you for that explanation!

I will be using polished aliminum, not polished metal and some dark aluminum.

I used revell acrylic as a base coat. ive used it before on my f86 and nothing bad happened. i just looked in my wip shots of the f86 and even then my base coat had orange peel and i sprayed without sanding and got a beautiful finish.

My god that website is horrible! it hurts my eyes!

[Alan P]

well... FIVE coatings before alclad LOL

You may scoff, but the results speak for themselves!

[AdriaN (MLT)]

Ok... so i begun sanding the black using first 4000, then 12000. the paint definitely feels much smoother!
BUT on some areas the grey primer showed through because either there was dust in the black paint or the detailed was raised and got sanded more or i pressed to much.

What i'd like to know is... can i still go about painting the polished aluminum? or do i have to re spray the black?
I know polished aluminum is very sensitive and i wouldn't want the final finish over the gray parts to come out different than the black parts.

[little-cars]

Polished finishes work like a mirror. The imperfections in the layer below the polished aluminium effectively reflects the light back and gives it the polished look.

The alclad paint really just changes the surface colour, so any imperfections will be seen.

The secret with alclad is in the black coat.

Alclad say gloss black enamel, but some acrylics do work.

As I said any imperfection in and on the black will be seen, the secret is in the preparation, sanding marks and fingerprints included.

The best situation is to spay a perfect coat of gloss black, then two thin coats of alclad over the top.

Before you go any further, I would try a test. airbrush some gloss black on a bottle. Sand half of it as you already have, then clearcoat it, then spray a couple of quick coats of alclad over to see the difference.

Paul

[pacificmustang]

Adrian, you need to respray the black over those areas that are grey, so that you have a uniform black coat

Bruce

[AdriaN (MLT)]

Adrian, you need to respray the black over those areas that are grey, so that you have a uniform black coat

Bruce

I did re spray the model and got orange peel AGAIN! I tried lowering the psi. Tried spraying wet coats. Didn't work.

I've decided to polish it using a softer grade than 4000. Maybe just 12000. Like that the sander won't sand through the black in raised areas.

[Alan P]

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Edited May 27, 2016 by Alan P