[Storm]

I am considering acquiring a S&W 669. The slide is in quite good condition but the frame is pretty lousy. There's a good amount of wear and it's going to need a new coating. My understanding is that the finish is done by anodizing the aluminum. I also understand that anodization adds strength to the frame. To refinish the gun it will probably be necessary to strip/blast what's left on the frame now, and paint (assuming my smith doesn't do anodizing). How much strength is lost when the anodization is gone, and does a good gun paint restore any of that strength that the anodization provided? I know that anodization protects against corrosion, but I'm concerned about the strength issue.

[gb6491]

Quite a bit of surface hardness is lost when removing anodization. This would be a major concern (at least to my mind) on bearing surfaces such as frame rails and pin holes. You also lose some surface dimension. Removing it from the rest of the frame surfaces would probably make them a little more subject to dents and scratches, but not of major concern strength wise. I think if you masked the rails and pin holes (any high tolerance areas as well) then prep the other surfaces for paint you could achieve good results.

Electroless nickel plating might add some hardness to un-anodized alloy. It needs to be prepped with something like Zincate (http://www.caswellplating.com/kits/zincate.htm) before it can be applied. The Zincate might be a good idea when painting a bare alloy as well.

Another thought would be to use a paint/coating that does not require removing the anodizing (or a blasted surface; cleaning up a small area shouldn't hurt much). Some examples would be Duracoat, Cerakot and Cerama-Coat (I've only seen it in black). Some of the coatings suggest they have increased wear resistance. I did my SIG 229 in the Cerama-Coat, over the existing worn/damaged anodizing, with good results. It has even resisted wear in the rail areas some (about 350 rounds through it):
http://i33.tinypic.com/egqogj.jpg
Remember to mask any holes before applying spray on finishes.
Regards,
Greg

[Storm]

Thanks Greg, that is most helpful. I'm going to let my gunsmith handle this one and will have him to avoid the rails and pin holes. He really knows his stuff and your info helps me make the decision whether the gun is salvageable. I think the gun is probably worth the effort.

[Storm]

Removing it from the rest of the frame surfaces would probably make them a little more subject to dents and scratches, but not of major concern strength wise.

I've done some more research on this and the above quote is exactly correct. I've found references to conversations that folks have had with Smith and the coatings on Smith frames have nothing to do with adding strength/integrity to the frame (although it might in some slight manner) but are about protecting the gun from corrosion and damage from scratches. The gun coatings that Greg has mentioned should do the same thing and with the range of colors of something like Duracoat a pretty good color match to the original frame should be possible. To me this opens up a "restoring" a whole range of weapons that I had previously considered off limits.

As an FYI, I also found references to folks being told by Smith that GunScrubber will remove the clear coat on frames. I would assume that this wouldn't be the colored cosmetic coating but some coating applied over that. This was in reference to a Model 642 so I'm not sure whether there is a clear coat on semi-auto frames.

But, the bottom line is that anodizing is not a strength/integrity issue (assuming there isn't extreme corrosion in its absence)

[EShell]

The above posts are more or less true.

Type III ("hard") anodize is a commercial process that adds considerable surface hardness and wear resistance to aluminum. Type-III anodize adds up to about .0015" to the dimensions, and penetrates by the same amount, rendering a total coating thickness of ~ .003". The pores in the anodize layer provide interstice4s to hold dye, which is sealed in to provide color. Type III is almost always dyed very dark colors and the typical AR-15 receiver sets and good qaulity accessories are Type III anodize.

Type II ("home") anodize is a done commercially, but can also be done at home. SEtup costs will be aorund $500, so it's not really worth it for one piece. Type II also adds considerable surface hardness, but the coating are about half as thick as Type III, adding .0005" to .001" to the dimension, with the same amount of penetration, typically rendering a total anodize layer thickness up to about .0015 to a maximum of .002". Type II can be dyed in a wide variety of colors and this is the process used for mainly decorative anodizing like paintball guns and motorcycle & model airplane parts, etc..

Neither process adds any structural strength, only surface hardness.

Anodize is stripped with caustic soda, the raw aluminum is then degreased, de-smutted (removes alloy materials form the surface), re-anodized, dyed as desired and sealed.

Aluminum alloys of any type without anodize is not at all wear resistant, and will likely gall under any sort of friction load.

There are quite a few commercial anodizers around, and prices to do something along the lines of your frame will be $125 and up.

[Mac's]

Depending on how bad it is, a good re-finisher may just lightly abrasive blast the metal to break the gloss and then use an Alodine soak to "touch up" the bare spots.

Alodine is a cold chemical soak used by a lot of industries in place of normal Anodizing to harden the surface of Aluminum. (It's a lot easier to use) There has been some mild controversy in the metal treating industry over whether Alodine is as hard as conventional Hard Anodizing. Some even claim that it's harder.

No, it's not pretty. In fact, it's downright ugly until it's coated. I don't know if it's harder or only close but it has an excellent reputation and does a great job of preparing Aluminum for a spray on finish. Keep yer powder dry, Mac.
Tuff-Gun Finishes. The Name Says It All.
Mac's Shootin' Irons
http://www.shootiniron.com

[Storm]

Hey Mac, thanks! BTW, you refinished a PT92 for me and did a fantastic job. You may well end up with this 669.

[Storm]

I picked up the 669 today. I gave it one last good long inspection at the shop and the answer as to what was up with the alloy frame finish became obvious. The grips were hazed over and I had thought to myself that the culprit was probably full strength GunScrubber or some such chemical. Then I recalled that Smith had said that GunScrubber would remove the clear coat. I looked at what I had thought was pitting and wear and realized that these were raised areas, actually damaged clear coat still on the gun. I scraped away at one of the areas with my fingernail (as I was going to buy the gun anyway) and the damaged clear coat came free leaving a smooth surface underneath. Having today off I just spent the last hour or so removing the remaining damaged clear coat leaving a finish underneath, that I assume to be "fully" anodized, that should require no further action. There's still a little clear coat here and there, but I'm going to pick up some regular GunScrubber (had used polymer safe) and get the rest off. I can actually use my fingernail to remove it as it seems that once GunScrubber hits the coating it's greatly weakened for good.

As of right now I think that the finish of the gun will only improve with further cleanings as the gun is used. The hazed grips came back as new with some CLP and a silicone gun cloth. The slide/barrel on this gun is absolutely pristine. I think what happened here is that someone shot the gun one or two times, cleaned it and screwing up the frame finish, and put the gun aside for a long time, probably out of disgust for the damage. I can still have the frame Duracoated, but it's now good enough that there really is no need.

I'm a pretty happy camper and will be able to evaluate an alloy framed gun next tie around.

Thanks again to all.