Hard Anodized Scope Mount

[Philip Dedmon]

OK all you color freaks (me included) check out this hard anodized scope mount. A local custom knife maker has started up a hard anodizing line. I have included a link with his email so if any of you guys would like to have your scope mount or anything else aluminium you have hard anodized in you favorite color.

cself@bellsouth.net

[uscbigdawg]

Sweeeet!!!!

[Kingman]

Nice,

Though I use Jpoints have to find something that needs color now on that one.

[warpspeed]

That looks cool Philp. How much ?

[Shipster]

SWEEeeeeeet!!! I like the RED That's Hot! RED and Black is a hard combo to beat!

[SELF Knives]

Hi All,

Just a quick note to clarify...the parts on Philips gun are Type II anodized and not technically considered "Hardcoat" or "Hard" anodized. I do offer both types but there are some differences with regard to color options. The process for type III (Hardcoat) and type II is very similar but color range for "Hardcoat" is limited to black and dark shades of green. This is due to a small surface pore size for a Type III anodized part.

The distinction in performance between the two is somewhat exagerated since the both surfaces are very hard (approaching the hardess of a saphire). However, in extreme wear applications the Harcoat does perform a little better. Both process offer an increase in abrasion resistance, are impervious to most chemicals normally used in and around firearms, and make cleanup easier.

An example of a commercial hardcoat surface would be the OD green surefire flashlights such as the M2.

Of course the "snake oil" chemical suppliers are allways touting new potions to produce a "hardcoat" like surface that can be colored like type II but so far I'm not aware of anyone who has perfected it. I am, however, continuously testing new products and I've found at least one that offers some promise.

Anyway, thanks for the positive response.

Cecil Self

SELF Knives

[MoNsTeR]

Think you can do Dawson basepads? I'd love some green ones. I've looked, but I can't figure how you get 'em apart.

[SELF Knives]

I think so...although I really need to look more closely at one before I say for sure. I'd be happy to try.

Cecil

[Philip Dedmon]

I am glad to see that Cecil posted all the correct 411 on the anodizing. It is obvious he is the one with the engineering degree.

warpspeed, you need to contact Cecil for pricing.

Here are photos of the scope mount & mainspring housing on my steel gun he did. Hope you enjoy.

[SELF Knives]

Monster,

I studied a couple of the Dawson base pads last night and I don't see any problem in doing them. If you're interested shoot me a note and we can discuss.

Thanks and take care,

Cecil

[Kingman]

How about AR uppers lowers possibly handgaurds etc. Is your tank big enough.

[SiG Lady]

Yesssssss... What Shipster said...!

[Wakal]

Oh, was that a big ole can of AR-shaped red worms?

(me too!)

Alex

[Kingman]

yep, yep.

No answer yet. Just imagine a black and red ar.

BAD

[SELF Knives]

Hey, that does sound interesting. My tanks are big enough to do an AR and I'm kinda itching to try one.

Cecil

[Kingman]

pm me your info and a number. I will get ahold of you next wk sometime.

I am building 2 right now.

[DJPoLo]

Think you can do Dawson basepads? I'd love some green ones.

My wife would love some green ones as well. I want in on this project when you do it.

-Chet

[Patrick Sweeney]

OK, time for some technical questions, not directly related to a specific project.

Starting with already anodized parts: How can you turn a black part into something with color? Do you have to strip the old off? Or just add the new? What does that do to the dimensions of the part? Does it matter if the old is Type II or Type III?

Is the selection of II or III also dependant on alloy? Are there aluminum alloys that can't be anodized? Do you need to know what the alloy is, and if so, to what level of specificity?

[SELF Knives]

Good questions. Let's start with a primer on what exactly anodizing is and isn't. A bare pure aluminum surface exposed to the atmosphere will begin to form a layer of aluminum oxide almost immediately upon exposure. Under natural conditions, this layer is very thin and loosely bonded but it does protect the aluminum surface from corrosion in most cases.

Anodizing is a means by which we can speed up this natural process, make it thicker, more tightly bonded, and denser. The aluminum actually grows a layer of aluminum oxide on itself and is then transformed into Aluminum Hydroxide and finally Hydroxide Monohydrate. Typically this layer is between .0005” and .001” thick for Type II anodizing and from about .001” to .002” thick for Type III. In both types approximately half of this thickness grows INTO and surface and the other half grows OUT OF the surface. It is electrically non-conductive and extremely hard.

It is not a coating and therefore doesn’t hide anything. If there are scratches on the surface before it is anodized, there will be scratches on the surface after anodizing.

Viewed from above and under very high magnification, this layer has the appearance of a honeycomb. These hollow cavities absorb the dyes and allow us to color the part to our liking. Once the part has absorbed enough dye to obtain the desired color depth, the surface is sealed to reduce color fading and to prevent the surface from soaking up other contaminates such as oil, sweat, greases, acids etc.

The limiting factor is anodizing layer thickness is that fact that electrical current is the driving factor in developing this protective layer. As mentioned above, this layer is not electrically conductive so as the thickness grows, the ability of the surface to conduct current falls dramatically.

Eventually we reach a point where growth ceases. If we try to raise the voltage to overcome the resistance of the surface, we will achieve some growth but will also begin to pit and erode the surface. If we then were to cool the anodizing bath and add a chemical to allow us to boost the voltage without damaging the surface we could keep building a thicker layer but the pore size would be much smaller due to the increase voltage (in general higher voltages favor small pore sizes). The process just described is Type III or more commonly referred to as “Hardcoat”. The reason Hardcoat can only be dyed black and dark green is that the pigment size of most of the other colors is larger than the surface pore size and the color simply won’t absorb (or if they do absorb the appearance can be spotty or lightly shaded).

Ok, now to address the specific questions.

How can you turn a black part into something with color? Do you have to strip the old off? Or just add the new?

The existing anodized layer must be stripped off, the new layer re-grown, dyed, and sealed.

What does that do to the dimensions of the part?

Since we’re going to “re-grow” a new anodized layer after we strip off the old and since we’re talking about extremely thin layers in the first place, we would ultimately expect for dimensions to change very little if at all. Having said that, if I were doing an AR I would try to mask off the interior so that only the exterior would be affected.

Does it matter if the old is Type II or Type III?

All being relative, I would expect to loose more surface material and therefore experience a great change in dimensions when stripping Type III and going back with a Type II. Again, the change would be very small but is still worth considering in the critical areas.

Is the selection of II or III also dependant on alloy?

Not really. Most wrought alloys can be anodized by either method without issue. However, due to alloying elements, some are more difficult than others.

Are there aluminum alloys that can't be anodized?

Again, some alloys are more difficult that others to anodize. The 6000 series alloys are probably the easiest while the 2000 series are probably the most difficult. This is due to the high copper content in the 2000. Copper is the major alloying element in the 2000 series, Magnesium and silicon for the 6000 series, and zinc for the 7000 series. Most machined AR receivers are machined from 7075-T6 due to its strength and hardness. The presence of non-aluminum can be controlled with a thorough desmutting step prior to the actual anodizing step. It is common to see color and shade variations in different alloys.

Cast aluminum can be the most challenging to anodize, particularly if you don’t know what it is. This is the culprit that causes the most headaches and the worst part is that there really aren’t any rules of thumb here. You never really know how big of a pain it’s going to be until you try it.

Do you need to know what the alloy is, and if so, to what level of specificity?

It certainly makes things go smoother if you know what the alloy is but the nice thing about anodizing is that, as long as you haven’t sealed the part after the dye step, you can just bleach it out and start over until you get the results you’re looking for. So, with a little trial and error, it’s not absolutely necessary to know what the alloy is.

That's it in a nutshell. There's a lot more technical stuff in the nuts and bolts in case anyone is interested but this is the jist of the process. Hope that helps.

Thanks to all who’ve made it this far,

Cecil