Going to try arma-coat (like duracoat), some questions first.

[XZIVR]

Okay this is mainly for people who have tried this paint before..

First of all, surface prep. I checked and I don't have access to an aluminum oxide blaster. I'm doing an M4 metal reciever and it still has its factory finish, which actually seems pretty durable.. What do you recommend I do? Apparently you shouldn't use sandpaper, and I couldn't even strip the factory paint of with acetone.. Should I just try painting over it and hope for the best?


Secondly, baking.. It says to bake at 200 F. I'm a little hesitant to do that because I'm afraid I may warp the potmetal. Oven doesn't go any lower, either. Should I just hit it with a heat gun for an hour or two?


Any help or advice would be appreciated..

[R1ghty]

I'm not too sure that a localized 500+*F flame would have less chance to warp than an oven at 200*F

I'd image the oven would be the way to go. If you don't want the full 200*, set it to 200*. Put the receiver in right away and take it out when the preheat beeps(oven hits 200*).

[XZIVR]

500* flame? It's an electric heat gun. like a glorified hairdryer. Nowhere near that hot. :P

[ShelledPants]

Originally Posted by XZIVR

500* flame? It's an electric heat gun. like a glorified hairdryer. Nowhere near that hot. :P

Maybe you've got your C and F mixed up, but my heat gun ($30 canadian tire) easily goes past 300C ... which is over 500F.

[XZIVR]

on high or low? And let's not assume the output air temperature is necessarily going to be the temperature any part of the reciever gets to.


Anyway, any ideas on surface prep guys?

[Kokanee]

Try baking it with the oven door halfway open, that should reduce the temp inside.

[MultipleParadox]

Localized heating will have WAY much more chance to warp anything than heating uniformly the whole piece. The high temp you will have at one spot will dilate much more than the lower temp spots, let alone the parts still cold which will not dilate at all. Result, warping.

Oven would be the way to go. If you've got a convection oven, even better. I would say use that.

Disclaimer:
I'm in no way knowledgeable about dura/arma-coat, or never had to bake any metal piece like that. But to me, this is just common sense. Take it for what it is

[R1ghty]

Originally Posted by MultipleParadox

Localized heating will have WAY much more chance to warp anything than heating uniformly the whole piece. The high temp you will have at one spot will dilate much more than the lower temp spots, let alone the parts still cold which will not dilate at all. Result, warping.

That was my point.

When you said heat gun. I thought open flame torch.. Knowing the electric heat guns can hit 500*F is nice though ;D


Testing to open door would be a way to go.. put it to 400* and open the door.
See if the temp drops. It may just Bump up the duty cycle of the burner.
(with door closed burner is on 50%@400*F, with door open burner is on 95%@400*F)

[XZIVR]

I think the part you guys are missing here is that with a heatgun you can heat stuff pretty evenly if you know what you're doing. I'm not just gonna go hurrrr, turn it up to max and hold it on one spot for an hour. My question about baking was more about whether it would be safe to run potmetal up to 200 degrees or not. My gut says yes, but thought I should ask.

What I would really like to know though, is what to do about the surface prep.

[EagleDriver]

Originally Posted by XZIVR

First of all, surface prep. I checked and I don't have access to an aluminum oxide blaster. I'm doing an M4 metal reciever and it still has its factory finish, which actually seems pretty durable.. What do you recommend I do? Apparently you shouldn't use sandpaper, and I couldn't even strip the factory paint of with acetone.. Should I just try painting over it and hope for the best?

If you don't media blast the original finish off then don't bother with the arma-coat. It won't be durable due to the original finish underneath.

[aZn_triXta07]

Originally Posted by EagleDriver

If you don't media blast the original finish off then don't bother with the arma-coat. It won't be durable due to the original finish underneath.

I've wasted time and duracoat before by not taking the appropriate measure to properly prep my surfaces before painting.

This stuff isn't cheap so take the time and do it right.

I generally give the parts a bath in lacquer thinner to degrease it or use the TruStrip Degreaser provided by Duracoat before either blasting them with aluminum oxide. Glass beads would also work.

After I do my coating I let it air dry a bit before putting it in the oven @ 180 for an hour.

[XZIVR]

Okay, so glass bead blasting does work? The arma-coat site says not to, something about bead blasting leaving a more polished surface.. Well, if it worked for you, maybe I'll just do that.

[Kos-Mos]

The original finish should be anodizing. To remove it, you have to remove the top layer that became a lot harder in the process. That is the reason why you need to clean it and blast it. There are chemical alternatives if you can't find a pressure blaster. SuperClean and Easy-OFF will "attack" the material. If you are VERY careful and don't leave the stuff on for too long, it can remove the finish. For SuperClean, neutralize with vinegar when done. Not sure if Easy-OFF is alkaline or acid...

Oven is the best solution. It's not the heat that warps it, it's the cooling-down.
Over at 200F should be good. When done, turn-off the oven, open the door a little (that little step) for about 30 seconds and then close it. Let the over cool down overnight.
If you have a convection oven, turn that on too. More even temperature.

You can cook motherboards at 385F without damage... I guess your receiver will be fine at 200F. Also, heatguns go WAY over 200F, usually around 500F.

[EagleDriver]

Fine grit aluminum oxide won't change the surface of the gun like bead blasting will. Bead blasting can make sharp edges/corners rounded. And yes, it gives it a smoother finish that is harder for a coat to adhere to. Any automotive body shop should be able to blast the parts for you if you can't do it yourself.