View Full Version : Another parkerizing question...
April 21, 2001, 01:29 PM
I'm now convinced that high-tech finishes are not worth the money, I'm going to reparkerize those firearms that need refinishing. I've field-stripped an 870 Express, and notice the ejector spring. This cannot be removed.
How will prkerizing affect the "springy" qualities of the spring? Will the etching destroy spring steel?
April 22, 2001, 02:57 AM
I don't have an 870, so I am not certain which spring you are talking about, but it would have to be a VERY fine spring (like a spring you might find in a witch!) for a surface treatment to affect it significantly.
April 22, 2001, 03:10 AM
That's the point: The ejector spring is a delicate little leaf spring staked down to the interior of the receiver
It cannot be removed and reinstalled prior to prkerizing except with a lot of trouble - damn two-step rivets holding it down...so this paper thin spring might get etched to death, huh?
April 22, 2001, 01:46 PM
Can you quantify paper thin? If it is really 0.003" thick, like a sheet of paper, then I would hesitate to etch it. My guess is that it is more like 0.025" or 0.035" thick, in which case you probably don't need to worry. (liability disclaimer goes here!) I am a mechanical engineer, but I have a LOT more experience with working aluminum than steel. Typical (non-paint) surface treatments are pretty thin ... I would consider 0.001" to be THICK! I did a quick search on the 'net and couldn't find a specification for the Parkerizing process anywhere. Sorry.
Is this spring stainless steel by chance? Take a magnet and if the spring is non-magnetic then you don't even need to worry! If it is magnestic, but shows NO signs of oxidation then either it is a magnetic stainless (many heat treated stainlesses are magnetic) or you take REALLY good care of your 870 ... in which case I would have to question the need to refinish it!
If it really is paper thin and looks to be a non-stainless steel, then you will have to decide what the risks are if its characteristics get modified. In this ugly scenario, all may not be lost. There are probably masks that you could apply to the surface of the spring that would protect it from the solution. They would have to be able to survive the 200 degree phosphoric acid, though.
Enough blabbering ... good luck,
April 22, 2001, 02:07 PM
Actually, it turns out that I may have to remove the ejector assembly altogether, to clean and park those parts. Which means that the ejector spring can safely be kept out of solution, and restaked onto the receiver when the refinishing is complete.
Besides that, Saands, is there a hydrogen embrittlement relief step after the phosphoric acid bath, that you know of?
Thanks again for your interest...
April 22, 2001, 10:57 PM
I do not know of any process step in the typical parkerizing process that would rid the substrate of hydrogen. If it concerned you, a simple bake should help drive any hydrogen out of the steel. My guess (just a guess mind you) is that the parkerizing solutions don't have any constituents that would poison the ability of the hydrogen to recombine into H2 and just bubble off. I'm no chemist, though, and I refuse to pretend to be one! I am in the process of putting my first parkerizing rig together. I think that it will be the way to go and I intend on getting a chemical kit from:
which looks like it will arrive well documented.
April 23, 2001, 12:54 AM
Saands, thanks for the link. I had been thinking of going with Brownells' zinc phosphate parkerizing solution, figuring that this would approach the gray-green that I love. And thanks for the tip on embrittlement relief: what temperature bake?
April 23, 2001, 08:08 PM
FYI, if you like the 'Park' look, consider this. As a gunsmith, when I have a customer who likes the flat look of Park, but doesn't want to parkerize a particular firearm, here's what I do.
I use a 'soft' bead in the sand blaster. This gives a softened look. I then caustic blue the firearm in question. The look is almost exactly like a parkerized firearm. I have set two pieces side by side and 99 out of 100 people can't tell the difference.
And the 870 CAN be refinished with the ejector still in place. That's how the 870 was finished in the first place. Hope that helps.
April 23, 2001, 11:01 PM
Romulus ... If I wasn't so damned curious myself, I would have told you to look for the info yourself :) ... but I am THAT curious and this is what I found: Typically if a sample has the need for a hydrogen embrittlement relief bake (I'm still not sure that Parkerizing qualifies here ... but that seems to be beside the point!) then it seems to be the consensus that the bake needs to happen within 24 hours of the hydrogen being deposited. "The present aircraft standards and AMS 2406, average 3 hours post plating bake at 190 centigrade" (375 F) ... they say post plating because plating (especially chrome plating) is where the highest exposure is found.
Hope this helps ... I did put in a request for some info on whether or not this step is necessary. I'll post the answer if it surfaces.
April 23, 2001, 11:18 PM
Saands, thanks for taking the time...didn't expect you to do research, I thought you might know off the top of your head. On whether 375 degrees farenheit can affect the heat treatment of steel, I'll do that bit of research myself...he he, thanks again.
Wallew, I appreciate your input. I understand that a bead blasted blue finish can be mistaken for a manganese phosphate jet black parked finish, but I'd like to achieve the gray-green tone of parkerizing, the old GI look, the classic patina that you get with zinc phosphate.
Thank you both
April 24, 2001, 10:15 PM
Romulus ... Now THAT ... I know off the top of my head! No ... even if the heat treated steel was SUPER hard. If we were talking about a sample that had just been quenched from a high temperature hardening, 375 might start the tempering process ... which would be good, but most tempering, even of knife blades which are trying to end up REALLY hard, go a fair bit past 375 F. The action should already be tempered well beyond that state.
ps ... I would not have looked it up if I wasn't interested myself ... no worries! Got honest technical questions? Ask! I might have the answer on the tip of my tongue, and I might not have the answer right away ... but if it is an interesting question ... to me ;) , I'll find the answer eventually! I'm more curious than your average bear.
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