doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Annealing Problem - Help and Advice requested!

Hi, folks,

It appears that my kiln, irritatingly, dropped its power I saw this when it had gone from 820 to 750 degrees mid way through the "hold" process of 1 hour of the annealing time.

I've now ended up with a hard crust (Which I assume is the old hardened metal" on the outside of each of the parts I have annealed.

It's probably an irrecoverable disaster but I wanted to check to see if anyone might advise on how I can remove this. I've taken a photo of one of the side plates that I have cleaned up next to one yet to be cleaned and you can see the mess the other one is in. I can of course clean the hammers and the side plates in the same way. My problem is the action.



Now clearly I'll have to get the gun re-faced which is irritating (I think I will anyway) because the surface I remove on the action face will be enough to create a gap. But how the heck am I going to get this layer off the inner parts of the action? Does anyone know of a chemical that might just take off the crusty metal??

Any help much appreciated!!

PS I followed Oscar Gaddy's piece from the journal a few years ago.

Regards,
Tony

Nitric acid will clean it like a new piece of metal in minutes. Be very careful with nitric acid and read all the warnings and heed them to the letter. You may also try some Naval Jelly rust remover.

What I think I see may be the result of air intrusion into your crucible. You did use a crucible packed with charcoal dust, correct? Or a vacuum furnace would be even better.

I have no idea but i certainly hope it comes out ok.

Didn't you say in an earlier post that you used aluminum foil to exclude the air? And that the foil had melted and disintegrated? If that's the case I fear you may have done irreversable harm to those parts.

The old toolmaker method of foiling in a heat treat oven employs stainless steel foil, tightly sealed over the part which is wrapped in newspaper. The foil must be sealed air tight. I've seen my friend literally TIG weld the foil shut to ensure this. The newspaper burns and consumes the oxygen. This is a time tested method.

Hi Hammer, yes I did and I didn't it appears use a completely air tight box either. I can get any of the foil off with some elbow grease so I don't think that has done too much damage.

I can't get nitric acid here as an individual and frankly I don't fancy playing with that stuff. I could try the rust remover but I'm not sure that will work will it? it's more like a hard but removable serface. If I gently tap the surface it comes off like a crust.

T

Muriatic acid (HCL) is much safer and easier to get at any hardware store. Mix it 50/50 with water and immerse the degreased parts until clean. After cleaning, rinse the parts well with baking soda/ water solution to neutralize acid. Apply WD-40 or some other water displacer immediately as the metal is chemically clean and will rust in a heartbeat.

OB

Guys, something like this worth a try?

Thing is it's quite a hard shell not really rust or will it still work??

http://www.halfords.com/webapp/wcs/store...yId_165594#tab3

If you are successful in salvaging your parts, perhaps it is time to practice on an old action, or various junk parts before you try to case harden that lovely old Greener. I've never been keen on re-casing old guns. I know it can be done without damage by expert craftsmen, but those fellows have had years to perfect the process. Some things are best left to the experts. Good luck and keep us informed.

Hammergun, lesson learned I say but I think I can recover it.

OB, this seem right stuff?

http://www.mistralni.co.uk/details.php?id=70

I'm with OB, Muratic Acid (swimming pool acid) will clean the parts like new....any crustation or oxide will be removed A.S.A.P.....use heavy nylon fishing line to submerge each part, then dip immediately into a fresh water pail/bucket....inspect and re-dip as needed.........then as OB said, oil immediately.....

I use it at 75 acid- 25 water- (sometimes at 100% acid) and have had great results with all kinds of metal parts, guns, airplanes, engines and so forth.....you must stand over the process as the time submerged must be watched........don't run off to answer the phone..........

Do this process outside and do not breath the fumes.........common sense rules here.......and have a water hose running slowly along side this process.......

If you have an oil stained concrete driveway, use the muriatic acid to clean your driveway while you're at it.

Thanks guys. Once again here in the UK I can't seem to get hold of it higher than 36% will that do the job albiet slower?? thanks chuck for the tip!

TT

this is the strongest ive found so far fellas;

http://cgi.ebay.co.uk/Hydrochloric-Acid-36%25---Brick-%26-Patio-Cleaner-5-litres_W0QQitemZ130371604843QQcmdZViewItem?rvr_id=&rvr_id=&cguid=c354b2321230a0aad3b48f74fefec0d3

Surely they sell "swimming pool acid" in the UK...which is "Muratic acid"..............in the U.S. it can be purchased at most grocery stores in the warmer climate areas...........I know they sell it in Italy and Spain because I have bought it there.......?........U.K., not sure...........

And Chuck, I didn't think your cars and trucks leaked oil.....?............You could also use it to clean your BBQ grates.........!.......(probably against the law in California...?)

will keep trying Doug might find it somewhere...that 36% brick cleaner not good enough?

Tony:

I think the Hydrochloric Acid Brick cleaner @ 36% would be very weak for etching and cleaning metal parts..........JMO.........I would call a 'swimming pool' supply house in one of your larger cities, I am sure they would have Muratic Acid full strength...?.......Any good hardware store should also have it....?........Maybe your laws do not allow full strength acid to be sold...?...........?......

Yep OK will try but the UK is extremely strict over this sort of crap...crazy...will try pool supplier tomorrow

Cheers

http://en.wikipedia.org/wiki/Hydrochloric_acid

The link above will tell you about hydrochloric acid.

I was thinking common "pool supply" muriatic acid was quite a bit less than 100%, thinking around 40%. Turns out that about 40% is about all that can be produced.

The strength needed seems to be about 18% for steel pickling. 36% would surely be effective at stripping the oxide scale.

From wikipedia

Pickling of steel
One of the most important applications of hydrochloric acid is in the pickling of steel, to remove rust or iron oxide scale from iron or steel before subsequent processing, such as extrusion, rolling, galvanizing, and other techniques.[6][8] Technical quality HCl at typically 18% concentration is the most commonly used pickling agent for the pickling of carbon steel grades.

MuraMic Acid.

All steel pickling operations I have seen use heated acid. The heat, of course, accelerates the action of the acid and would permit a lower concentration of acid to work as well as a higher concentration would work cold. In addition to Hydrochloric, I've seen Nitric and Sulfuric acid used, and Hydroflouric was used for pickling stainless steels.

I would follow the advice given earlier to babysit the process. You may find that a shorter acid pickle followed by a rinse and then wire brushing or wheeling would be preferable to waiting for the acid to eat everything perfectly clean. The parts may clean up nicely when they look like they are covered with black slime. You can always go back to the acid if it needs more time, but you can't replace good steel that gets eaten away.

I doubt that this had anything to do with your kilns' power loss at 750-800 degrees. The scale probably formed at higher temp when your aluminum foil wrap disintegrated.

That is it, but it seems to be very expensive. In the US, it is commonly sold in building supply and hardware stores as a cleaner for concrete, masonry and bricks. It is not very agressive on human skin, but the fumes are an eye and respiratory tract irritant. Use it outside, stay upwind of it and you won't need a respirator. I do recommend chemical goggles in case of splashes. If the 50-50 mix doesn't seem to be working fast enough, you can use it full strength while you watch it work.

OB

Hi guys, found a 20-30% mix and it appears to have done the trick over an hour or so. I have plenty of shining up to do but the worst is off. Thanks very much for everyone's advice here and I'll update my blog with photos and post here as piece get done so you can see the result.

I still intend to case color harden these parts now that I am on a mission. I'm having an air tight stainless steel container made so that the charcoal mix and parts don't get contaminated.

Cheers
T

Good Job Tony....glad it worked out for you.................

Good Luck with your project...keep us updated......

Best Regards,

I don't want to get the case color hardening wrong that's for sure so will be doing some scrap steel pieces first to make sure..

Cheers Doug.
T

Since so many people have helped with advice, please show us the after picture

PDD

Of course. No worries. There is actually one at the top of this page..but as I complete the others I'll photograph them.

Best
T

Hi folks, OK, been working hard with various lightway sanding tools to get the action back. Very pleased to be frank. It's back to where it was before the annealing skin! Doing other parts ready for case color hardening.

I've been given two old actions from my friendly gunsmiths so I'm practising on them first...

Regards,
Tony

Nice photos. Great catch.

And you are sure it is soft now, How?





Just checking.

Tony:

Looks good.......keep it up......!.........

Clapper, it's soft because you can just tell. The metal underneath is a dull grey and it's v easy to dent. Trust me...well I'll know when I try and color it for sure. But it is a dull grey.

I've actually just done another action. This time I wrapped in 0.002" thousands stainless steel foil. I also added some carbon charcoal to soak up any oxygen. It came out perfectly...annealed and dull grey and NO carbon....

Getting there PA24. I've got two old actioned..one already annealed...to try first.

T

Ballistix, you can do better than just guessing.
Find a hidden spot within the action and stroke a small file over it. If the file bites, the action is softer than the file, which is confirming, and all the engraver, and machinist need to proceed.

If you are going to learn and ENJOY vintage metalwork, might as well start out on the right foot.
No offense intended, just making sure for you.

Your first foray into the kiln was both exciting, and a little disconcerting.

Hi clapper, thanks for that will make sure Yes agreed the first kiln firing was both exciting and pant fillingly worrying!

I'm intent on getting this right. Thanks for the advice.

Regards,
Tony

Hi Clapper, as promised here is the latest work! I've created another post but wanted to make sure I replied to this one too!

After a couple of tests I decided to case colour harden the first part of my Greener. I'm quite happy with it and it's not too harsh. Pictures below and more on my blog.







It's one of those things you just have to try and experiment with. I plan to do the hammers and sidelock plates next.

If you are interested and want to see more the blog has more and the pictures are bigger there.

Regards,
T

Looks really nice Tony, good job mate.........


Best,

Thanks Doug