Thread: rust prevention

After machining I just heat to orange/red hot with propane, and then dunk it in used motor oil and it works great.Sometimes it gets 2 goes, but I am not sure it makes a huge difference.
I had some old diesel oil given to me a few months back, but haven't tried it yet.

Dave

I mostly heat to around 300C(on the stove) as I dont have any real heat in the shed. For small work you can get nice browns or blues to the color you like. I then dunk and let it cool in the oil(I'm really not sure this makes much differance but it makes me feel better lol). It seems to work well enough. If I really want black I tied a piece of wire to it and throw it into the wood BBQ.

Be a little careful as if you are doing many parts the oil can get very hot and ever flare up. Of course it depends how big your oil bucket is.

Stuart

becareful when heating to rust proof, say a centre punch you don't want to get it blue if you have already tempered and hardend it let alone going red because the term "losing your temper" doesn't come from a random saying, its about exactly that and the old blacksmith getting pretty wild because he has lost the temper of the steel.

just make sure the steel is clean (shinny) so you can see the colour change easier, light brown/dark gold is good, pleanty hot enough, heat and drop into (i use old engine oil) oil and let it cool in the oil.

Hi kraits,
Good point, I was thinking about MS, pretty sure Dave would have been as well, we just forgot to say it.
Stuart

As Stuart said I only use on mild steel stuff around the shed like handles etc. I don't do it on any precision stuff though.
Kraits brings up a good point if your doing something thats hardened.

Dave

Thanks everyone, it's one of those things you do in class but then never do in the real world and time goes by....but it will be handy for things I do at home!
As a longer term rust prevention method, How good is it?


Pete

I have found it to be good in the shed things I have done, but not sure about outside.

Dave

Seems to work pretty well and I am one of those (1 in 1000 is it?) that seems to have acid fingers. Have to wear gloves if I am working with brass.

Stuart

where i have found it to be most effective is on a knurl, polished parts tend to wipe clean quite easily

Originally Posted by pjt

As a longer term rust prevention method, How good is it?

I used the method on some parts of a door handle on the exposed side of an exterior door (note the parts don't come in contact with hands when the handle is used). They have been they for about 12 months (maybe longer) and look as good as the day I installed them.

In the middle of doing research into one of my medium term projects, gun bluing, which is a method of rust control. May help.

Military use similar process to commercial engineering shops which tend to use hot water phosphoric acid solution dips to help rust proof some components. (gives dull grayish black colour).

Browning. Used in very old guns ie external hammer type shotguns. This is brown rusting process, but after each treatment the loose rust is lightly scuffed off until you have a smooth brown deposit.

Hot water bluing. Submerse in boiling solution of nitrate salts. Apparently the ducks nuts of treatments for colour (if you want blue) and long term durability but also quite risky to your health.

Also listed is a caustic treatment which may be simply dipping in hot solution of caustic soda, though yet to confirm. I know that this can clean metal of light rust.

Heat bluing. Just heat with torch till you get the required colours washing over surface.

Heating and then dipping in oil clean or dirty. Hit and miss in terms of quality control for colouring but better than just heating or doing nothing.

Bottom line is that for this to be effective corrosion control once treated all surfaces are oiled. All treatments make iron less reactive (probably with exception of straight heating) and therefore less likely for iron to react to form rust a we know it, Some of the treatments produce a roughened and porous surface layer which absorbs oil retaining it on the surface longer. Chromium bores in engines are used to produce a similar effect to help retain oils on the piston liner.

If you are heating a carbon steel you should consider if what you are doing will produce hardening and whether this is an acceptable side effect or not. Somewhere on the net you should be able a heating colour to metal temp guide to help you operate in a safe region.

Thanks again for eveyones input, the collective knowledge and experience of fellow forumites can't be beat


Pete

Have any of you blokes tried a gun blue like this?

http://www.shooters.com.au/product.a...ID=1139&c=6327

or a hot salts process like this?

[ame="http://www.youtube.com/watch?v=qM_Z1Tax2k0&feature=related"]http://www.youtube.com/watch?v=qM_Z1Tax2k0&feature=related[/ame]

Chris

Just about to say that, gun bluing is pretty good and it has a nice colour to it as well and dosent rust.

Cooper