I took off the battered saddle wiper guard from my ML7, sanded back to almost shiny bare steel, and then applied the 4 stage blackening kit (degreaser, conditioner, ferrous blackener, dewatering) sold by Blackgates.
I followed the instructions closely, and was initially happy with the newly blackened article (although in places it did have a very subtle brown-ish shade 'underneath' the black. Didn't think any more of it.)
Now a few weeks later it has developed into some weird wipeable brown surface sludge. As you can see, the inner surface is a lot better, which leads me to deduce that it is an atmospheric reaction, since the inner face is effectively fully coated by the Nutto soaked felt wiper?
Please can someone advise as to what has happened?!
It has to be absolute bare steel. Did you leave the original Myford black where it still existed? Did you get any rust off? Iv'e never used Blackgates, but did you thin the blacking too much if it specified it? Even your inside surface looks patchy so I have to suspect your cleaning. Never handle it directly at all during or after cleaning it up; use two bits of wire in opposite holes and dunk it with them. The blacking needs to be in one go, over the whole surface, and there is no harm in leaving it in the oil at the end for longer. Hope that gives some clues.
I agree with DMR and Robbo. I've never used the Blackgates product, but I have used most of the brands sold by gun shops. The surface must be as shiny as possible, and absolutely clean – even a small fingerprint can ruin the result. And, as DMR says, give the item a really long soak in oil – if you don't, rust will start very quickly.
The gunshop brand I've found best is called (IIRC) G96, and it's a paste, not a fluid.
I made a naval cannon model in 2002 and blued it with this. It's needed only occasional oiling and touchup since.
Wash it in hot fairy liquid suds first, don't touch it with bare fingers when you take it out, and apply the paste while the metal's still hot – a stiff artist's brush is good. When it's taken properly, wash again, dry thoroughly and oil up. 3-in-1 is good, but so is olive oil – I've also had good results on an Opinel knife for camping.
Edited By Mick Burmeister 1 on 18/08/2017 09:47:37
Edited By Mick Burmeister 1 on 18/08/2017 09:48:22
Edited By Mick Burmeister 1 on 18/08/2017 09:56:42
+1 on the G96 creme, but keep in mind that no cold blue creates the same surface coating as a hot tank immersion process and the corrosion protection when oiled is never as good as the caustic or molten salts system.
If the item has a fine rust coating, you can put it into boiling water for a few minutes, which will turn the rust black, then rub off the rust with 0000 wire wool and you will get a finish similar to the original black.
Posted by SillyOldDuffer on 18/08/2017 16:27:43:Posted by Mick Burmeister 1 on 18/08/2017 09:44:09:
…
Nice cannon MIck. Is it a model of a particular gun? Also, how did you do the flare on the muzzle and the reinforcing rings?
Ta,
Dave
Edited By SillyOldDuffer on 18/08/2017 16:28:04
Thanks, Dave. It's a late 18thC 24-pounder, which I think first-raters like Victory carried on the middle gun deck. It was made from a set of drawings by a US engineer, Jerry Howell who used to sell copies for what seemed a reasonable sum at the time. It was supposed to be based on one on USS Constitution, and I anglicised it by changing the cascabel button and a couple of other details I can't remember.
I wish I could think of a neat and simple way to add the rope ring above the cascabel. I made little form tools to shape the reinforcing rings, and did the muzzle swell with 'fingernail' form tools, followed by lotsa work with a half-round file and then lots more with wet-and-dry emery!
As a boy I lived in Malta for a couple of years and the place had many old cannon and Victorian bottle guns lying about. I've always wanted to model one but never have. When you look into there are quite a few design features that seem to call for special treatment with form tools etc.. And now you've confirmed my suspicions!
Can't help with the rope ring on the cascabel except to suggest relabelling the display. My memory is awful but I think cascable rope rings are a late 18th century British innovation. So you could claim it's an authentic representation of an earlier gun. And if it's not true you can blame me!
Looks like the absence of a rope loop is to be expected on cannon made before the introduction of the Blomfield pattern in 1794. **LINK**
Given that ships of the line could spent years laid up in ordinary, I suspect that the earlier Armstrong pattern (typically confusing that two different Armstrongs a century apart gave their names to guns) would have remained in service throughout the Napoleonic wars.
I too like the heating and quenching in oil method for small items and have tried a few different oils with reasonable results. I tend now to use cheap supermarket rapeseed oil which usually works fine but have often wondered if there is a better oil out there. I seem to remember people advocating used car engine oil but the health and safety people said that was a no no as there were lots of nasty things in that. Has anybody found a safe oil that is better than rapeseed oil?
Don't do this job often, have used heat and quench in oil ,seams to work well. I use old engine oil, pref . diesel . It's very black , I always do it when no-body is watching.
Whale oil!!!!!! You'll be giving even me coniptions. Killing whales is outlawed by almost all countries, so where are you getting it from. According to t'interweb the trade in whale products is banned
I think whale oil is an even bigger no no than old engine oil ,but there may be a synthetic equivalent out there. Whether it is any good at blackening is another matter.
I recently tried Casey Super Blue from these folks… **LINK**
Usual caveats – just a satisfied customer.
Scrupulously clean and degreased (hot water and washing up liquid), and wearing disposable gloves, followed by a couple of wipes over from the bottle – no real need to dip it IMHO. Followed by rinse in hot water and then dried and oiled.
Not the greatest photo but the knurl and dial indicator holder here were done this way.
HTH
Jon
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