Sig aluminum frame decoating question

[Whats-his-name]

Howdo,

I have a rather worn Sig-Sauer pistol whose finish on the aluminum frame is less than desired (worn and scratched).

Can anyone tell me what the coating is on Sig pistol ali' frames and how best to remove the coating without affecting the aluminum?

I intend to recoat the frame (probably anodising) if I can remove the original coat.

Many thanks!

 

[rcmodel]

They were all hard anodized until recently.
I think they may plate or paint some of them now.

Removing the hard anodizing will get you into the softer aluminum.

If you are familiar with anodizing, you know the "hard" part is actually clear and can't be seen under the color died part.

I think hard anodizing is probably best left to the professional firearms refinishing shops who will know what needs to be done to it.

rc

 

[IndianaBoy]

It is anodizing. I am far from an expert, but it is difficult to remove.


I would send it to Robar, have it stripped and have their NP3 coating applied.

 

[Whats-his-name]

They were all hard anodized until recently.
I think they may plate or paint some of them now.

Removing the hard anodizing will get you into the softer aluminum.

If you are familiar with anodizing, you know the "hard" part is actually clear and can't be seen under the color died part.

I think hard anodizing is probably best left to the professional firearms refinishing shops who will know what needs to be done to it.

Thanks rc. I did wonder if it they were anodised (it's a 1992 P226). A close look at the damaged areas shows chipping of the coating which made me hope that it was a coating (i.e., painted) that could be removed without affected the aluminum. However, it doesn't exclude an anodised finish - bummer.

Would re-anodising with the current finish still in place be any good? I imagine at best the worn areas will turn a different shade of black and at worst it could make a complete mess.

----------------

Thanks Indi, I'll look into Robar out of curiosity at least.

 

[rcmodel]

I really don't know enough about anodizing to be giving any advice.

I just know you shouldn't remove the "hard" part or wear will be increased.

Early Colt Commanders would suffer feed ramp damage from HP ammo if you polished the hard anodizing off the feed ramp.

I'd think if it is chipping off, it needs to all come off and be redone from the getgo though.

rc

 

[BCRider]

I learned a bit about anodozing from my paintball days.

Now if it is chipping off then it is a coating and not anodizing. Anodizing is a method of colouring that alters the metal so you won't find a better bond and it would never chip. It'll scratch and is subject to being gouged by accidents but it will never chip away even from the edges of other damage.

If you're after getting it re-anodized then the anodizer will be able to strip the old anodizing off. It's a standard thing they can do. But depending on the finish you want you may want to get it back for polishing or direct the anodizer to media blast it to achieve the look you're after. A gloss or brushed look will come from a classy polish or brushed fine sandpaper surface while a dull matt look requires some media blasting with something soft like walnut shells to achieve the dull flatt surface. And polishing or carefully brush finishing it is more about elbow grease and time. If you're paying for that step it'll cost ya.

RC, you're almost right about the colouring but not quite. Anodizing is an electrical change treatment that alters the outer skin of the aluminium. The first step leaves open pores in the altered layer that are receptive to colouring dyes. Following dyeing the coating is boiled and that alters the outer layer crystals to close and trap the colouring. The anodizing is then hardened using some sort of cold treatment but I'm not sure where it fits into the process or how it is timed. But ask the anodizer if they can do hard ano'ing. Not all of them want to bother.

Now if you want to just Gun-Kote it or Duracoat it then there's no need to remove the old anodizing. In fact it'll act as a good tooth base for the new finish provided you seriously degrease it to remove any signs of the old oils that it has been exposed to over the years.

 

[Whats-his-name]

Thanks RC and BC.

I think I'll avoid re-anodising.

I looked up the Gun-Kote and realised I'd been overlooking something I've known about for yonks and that's powder coating (I always thought it was just alloy wheels that got this treatment - how naive of me!!!!). This seems to be the best bet for recoating an aluminum frame, especially after reading all the specs and wot-not.

Thanks all - I'm now off to powder-coat and make a stink with an oven.

 

[Mac's]

Do NOT powder coat your pistol frame!!! We regularly powder coat firearm parts but only long gun barrels, bipods, bolt handles, etc.....never frames or any parts that move. There are two reasons to not coat a handgun frame or any other moving part.

1...Powder coat is a thick coating and will interfere with moving parts. Powder coating the frame sounds good but you would have to mask off every single opening into the inner surface of the frame and the slide rails. Even a little powder in the mag well will cause interference problems.

2...Powder coat does not burnish with wear and will actually "ball up" and cause increased friction. (Jamming) If you get into the slide rails, you will work up some serious sweat lapping it out again.

A much better method for refinishing an Aluminum frame is to abrasive blast it at reduced pressure from a further distance. The idea is not to strip it clean.... it's to remove any loose scale and to etch the surface. Then soak it in Alodine for a few minutes. Alodine is an industrial "quicky" Anodizing solution. Many companies use it in place of normal Anodizing for things that will be painted or coated over. The areas with bare Aluminum will turn an ugly yellow color. (Don't blast laser etched serial numbers. They'll be gone forever)

After Alodining, coat it will a good finish like Gunkote. Of course, there are many other finishing methods out there... some better and some not as good. This is just one example but do not powder coat it! Keep yer powder dry, Mac. (No pun intended. It's my signature)
Tuff-Gun Finishes. The Name Says It All.
Mac's Shootin' Irons
http:;//www.shootiniron.com

 

[rcmodel]

That sounds like excellent advice.

After watching the OCC guys fighting powder coat build-up to get very crude Harley parts to go back together, I sure wouldn't want to use it on a firearm frame.

rc

 

[THE MACHINIST]

send it to sig sauer and have them redo the plating for you.