Any ideaa to clean the brass burner?

I have cleaned some of the brass parts of my Optimus 111 but the burner is very black and 3 days in oxydic acid has removed some of the black stuff but a lot remains.

Any ideas for chemical cleaning? Mechanical cleaning with 4 pipes in the burner doesn't really tempt me.

I might go for glassblasting, but that costs.

 

citric acid

 

@pbekkerh
Are you talking about inside the burner or outside?
Inside heat and quench, maybe use an old bicycle brake cable inner to remove some carbon mechanically?
Outside small Dremel wire brush maybe citric acid but it’s going to go black again anyway!

 

Thank you. I'm trying citric, we'll see tomorrow.
I might sell it, with these ridiculous prices, so it should look it's best

 

I have had some success with a wipe of rust remover, like Jenolite, where the phosphoric acid seems to shift the black. As with other acids, including citric, it will draw out the zinc and turn it pink if left on too long.

 

Yes thank you, I have seen that on some types of brass but not on others

 

@pbekkerh
As a last resort I put a strip of Duck tape on the back of a sheet of 1200 sandpaper then cut it into long, narrow strips . Put some metal polish on the abrasive side . With the burner secured in a vice, you can then use the strips to clean round the tubes .

 

Avoid Brasso or Duraglit, or any other ''brass polish'' with ammonia. The ammonia causes microscopic cracks in the brass -- very dangerous for a device that goes thru high temperature cycles.

 

Also avoid soaking for days in any sort of acid.

 

I cleaned up an optimus 96 with simple table catsup. Its mildly acidic and washes off simply.