Blueing over park?

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In the thread titled, "G1 handguard finish..." Derby FALs mentioned blueing over park, then in the thread with the great subject "Post Parkin' Depression" Dan at VOW mentioned it again. How do you go about doing this?

I've cold blued many steel mags with great success. They didn't look good, but it kept them from rusting and the blueing stayed on where there was metal to metal contact, unlike the paint. I have a new Hesse receiver that is missing much of the finish along the sharp edges, most of the front of the right side of the receiver wasn't parked (it looks like the raised surface from the voids in the cast didn't take the park and its still shiny), and the bottom is a chalky white. So, I'm looking for a way I can keep it from continuing to rust. I tried blueing over the park, but it didn't appear to have any effect whatsoever on the parked surface. The shiny nicks and edges became a bright royal blue, but none of the park changed in appearance. I degreased the surface by spraying it with brake cleaner, then putting it in boiling soapy water then I wiped it off w/ acetone. Is there anything special you need to do to the park to prepare it for blueing? Do you need to leave the blueing compound in contact w/ the park for a long time? I'm more concerned with protecting the part than I am with looks, so don't worry about helping me make it look pretty.

PS: Reading over the "Post Parkin' Depression" thread has made me really appreciate how simple it is to cold blue.

[Dan at VOW]

The best way I know of to blue over park is to carefully package your parts and send them to George Gouger at Double G.

Now that I've got the smarta$$ answer out of my system, I have used cold blue to touch up areas that got nicked or scratched during asssembly or trips to the range. Double G does his bluing the old fashioned way. He has the equipment and knowledge to turn out beautiful blue over park. This is done using the hot bluing process, with bluing salts and multiple tanks. I don't think you will ever get the results you want using cold blue. You will probably have to knock the sharp edges down with a file or sandpaper to get them to 'take' the blue. From looking at the Hesse receivers that Danno has brought into the shop, they look like they have a black oxide finish. And both of them were white, powdery looking, only turned dark after being oiled. Lots of casting marks, sharp edges, high and low spots in the receiver rails, charging handle rail, areas that had to be relieved at second face inside recevier. He did manage to get both of them up and running, though it has taken 4-5 times longer to do than with an IMBEL, Entreprise, DSA or other receiver. HTH, Dan.

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Thanks for the response Dan. I'm sure you're right about not getting a good result from cold blueing, but I'm cheap and not picky, so I'll take my chances.

I tried again. I left a puddle of cold blueing compound on the part for a couple of hours. Afterwards, I rubbed the part down with a cloth soaked in used motor oil. That's my cheap hack to try to get the finish darker. The part looks better now, but not by much. I don't know if it looks better from the blueing over the park or if it was simply from the rubbing and oil. The formerly shiny parts are now a royal blue, I've gotten rid of the surface rust, and the white sheen is gone, so I'll call it a success.

You're exactly right about the sharp edges on the Hesse receiver. I already have several cuts on my hands from the receiver, and I haven't even finished touching-up the finish or torqueing down the barrel. Two of my cuts are over an inch long! If I ever need to use this rifle in self defense and it won't fire, I'll just throw it at the guy.

high and low spots in the receiver rails, charging handle rail, areas that had to be relieved at second face inside receiver.

My Hesse receiver doesn't appear to have any of those above problems. While the right outside of the receiver looks horrible, the rails on the inside and for the charging handle look perfect. I worked the parts by hand in the rails, and everything looked fine to me. Disclaimer, the only FAL I've seen in person is this one today, so I'm simply stating what it looks like to my inexpert eyes.

The one additional problem I've seen is that the cut-out for the receiver cover, just behind the carry handle cut-out, is not to spec. It looks like they milled-out a round hole then didn't remove the material on the right side from about 120 degrees from vertical clockwise to about 150 degrees. Maybe, that's what you meant when you said "second face inside [the] receiver."

The biggest problem I found was that the bolt hold open channel in the ejector block looks like it was made with a rough hand file. I don't have enough of a machinist background to adequately describe how poorly this part looked. I spent two solid hours cleaning it up with a file, then 600 grit sand paper, then an emery cloth. Now, the part slides like glass in this channel.

The cut-out for mag catch was much too large for my mag catch. I don't know which part is out of spec.

Also, I don't think the fit between the upper and the lower could be better. It is so tight it takes a solid whack to get it open after pulling the catch back. Again, I know nothing about FAL's except what I've read here and from Gunplumber's video, so it's simply my guess that a tight lock-up is desirable.

[Hesse versus IMBEL] 4-5 times longer

I believe that based simply on what I had to do to get the bolt hold open part to fit. I haven't tried it yet, but I'm still hoping the barrel will time correctly.

With all of that said, I have one more knock on the Hesse. The serial number is unreadable. I'm going to have to find-out what it is supposed to be from my dealer and then remark it somehow.

PS: I guess most of the above should go in a post in the review section.

[Derby FALs]

Hot blue over Park will give you a durable black matte finish that will hold oil well. I've not had much luck with the cold blue over Park unless I got the metal very hot. Doesn't come out the same though.