Thread: blackening/blueing

There is no difference.
There are heaps (Hundreds) of slightly different methods.
The two biggest variations are those done hot, or those done at room temperature - called cold bluing
The most common methods are those used by commercial companies usually involving hot salts
The wikipedia article on "bluing (steel)" provides a quick basic overview of the general processes used..

If you dont need much done get it done commercially,it is not very exspensive.

One thing I forgot to add to my previous post is some people refer to blackening as heating metal and dipping it in oil which is a different process than bluing or blackening by developing Fe304 layers on the surface of steel.

Blast it!, I was hoping to blue a few things on the weekend but it was windy and as I do it outdoors the wind plays up too much with the gas burners. During week I had cut tops out of a couple of LPG gas cylinders so had new pots and all, a-bugga

I use Fuchs Colorsal. It is basically caustic soda and potassium nitrate, I think with possibly propriety additives. If I didn't have this I'd just use the two main raw ingredients which are easily available. Oh water is the third ingredient. Concentration of solution is important so that the boiling point is around 145degreeC. There are a couple of dangers with using it but once known they're no big problem.

Cheers.

Fuchs is a brand, damn hashes, I'll spell it differently. Fu$hs. Replace the $ with c. Hope it works this time.
Oh I see I must have originally spelled it wrong in the second para.. Which I have now corrected, just in case you are confused with my ramblings.

Dave,

In the first few photos of the thread below, you may be able to notice a difference between sump oil colouring of the little cast iron pointer and the subsequent chemical colouring with Blackfast. The flame and sump oil works well enough on some items and is hopeless on others. I thought it was insipid on the cast iron. Often, heating steel to blue and oil quenching provides a good finish.

https://www.woodworkforums.com/f65/bl...9/#post1217328

Starrett colours a lot of their steel components with a durable "black" finish. I like it, I'll post a few photos. Someone maybe able to identify the process used.

Bob.

"The flame and sump oil works well enough on some items and is hopeless on others"

I second this. First time I did it I though I had struck gold as the black finish on this small piece I made was outstanding. The next time I tried it though it was hopeless.

I have used the liquid chemical blackening compounds from 'janes kits' too. havent fully cracked it yet though. I found the finish to be thin and not very durable. Need to try it more before writing it off though.

Brendan