pickling Advice

[mildsteel2002]

Hi All
What is the best for pickling parts? Sulphuric Acid 10% or pickling paste. As i'm building Kozo's New Shay mostly in brass and Stainless i was tending more toward the 10% Sulphuric Acid. Any thoughts?
Regards Dennis

[pkastagehand]

I'm using the weak sulfuric solution. So far so good. I think I've seen threads here or on other BBS that talk of other things, like citric acid for one. I used sulfuric because I have a free source.

Paul

[kvom]

I use citric acid.

[grege]

I've used citric, sulphuric and muriatic acids at different times.

I found citric slower, but it was improved when I warmed it in an old crock-pot. It took about an hour to get parts clean. I was only using cooking type dry crystals from the grocery store though- there are stronger forms I think.
One major benefit is its relative safety. I tasted a drop with a little 'pucker' being the only side effect.

I mixed up a larger batch of sulphuric this winter for building my boiler diluted from car battery strength acid I got at the auto parts store. It worked quickly- warm parts would be done in 10-15 minutes. I did trash a sweatshirt though from what seemed a minor incident of air escaping the nearly completed boiler. I had gloves and goggles on at all times when using it.

Greg

[kvom]

An advantage of citric is that you can leave parts in the pickle a long time. If they stay overnight it's no big deal. And the safety aspect is not to be ignored.

[daveb1]

Hi Dennis,
I use a product called PH Down. It is used in pools to lower the ph in the water. It does not have the problems that sulfuric acid presents. I have never used anything else so I can't compare. Glad to see someone else building the New Shay. I have completed the frame and trucks and now working on the Boiler. How far along are you. What scale?

Dave Barker
Bow NH

[powderhorn01]

For something cheap, and not hazardous, use plain white vinegar. Warm it up in an old crock pot, and it works great. Just use it out in the shop or garage, or else the the woman of the house will turn into the war department and thump on your head.

If you are having problems with your brass turning pink, you have steel contamination present. Do not use any form of steel, including stainless to reach into the pickle, use copper tongs.

When I have to pickle steel, I use just enough for the job, then discard it, when done.

[mildsteel2002]

Thanks all for the advice looks like i will do some testing with white vinigar[ warmed] verses citric acid and save the sulphuric for the boiler when i get that far.
So far i have built the frame and boiler support and turned and machined all the components for the wheels of which i am using 516 stainless, at the moment i am waiting for cobalt drills to drill the holes for the spokes as i found some have work hardened,anyone else had this problem?.I have been making a lot of the jigs, so as they are ready when needed.I am building in 3/4 for 3 and 1/2inch track.
Regards Dennis

[kvom]

Drilling SS requires firm continuous pressure to avoid the work hardening. Cobalt bits will have the same problem unless the technique is correct.