stainless

[illuzion]

When trying to tig weld stainless steel (ie 304ss), I get discoloration from the heat, I know some people suggest using a copper backing block to localize the heat, but in some applications it isn't practical nor possible. How can the discoloration be removed after the fact on a part too large to carry around (ie a commercial kitchen range/hood). I have heard some rumors about using an electrochemical reverse plating process in a portable localized application to etch/electroclean the metal, has anyone had experience with this, or any product recommendations. Or does anyone know of a better way. I really didn't want to go crazy with abrasives and worry about disturbing the finish.
Thanks
illuzion

[imported_Blackplague]

electrochemical color reversal is not a rumor

I've seen it and used it. It is awesome. It plugs into a 115v outlet and clips to the weld bench or the part that your welding. It uses some sort of acid {not sure what it is}. You just wipe the felt wiper over the discoloration and pull the triger. It is so cool that the color disappears as fast as you can wipe the felt wiper over the weld {just like a big eraser}. The machine was expensive as i've heard {around 2600.00}. I can take a few pix of the scrap peice that i tried the machine with. I'll have to get the name of the company that makes it too.

[arcdawg]

i do kitchen hoods too, SMALL WORLD HUH? now blackpluage is 100% right !!!!!! we used that machine on every hood its the best way to do it im not sure about the acid that they use but man it made my life alot easier !!!

brian

[illuzion]

I still haven't gotten any details on this process/machine other than the fact that it exists, does anyone have a manufacturer/info on it?? Also I see no need to purcahse another expensive power supply, as I already own a really good programmable one that should be suitable for electroplating (the dynasty) since most advanced electroplating processes use nothing more than a high frequency pulse width modulated power supply, the simple ones use nothing more than a straight DC supply. I'm sure all I need is the chemical and a nice homebrew electrode (a sponge). I can't understand why this thing is $2600.

[mike40]

stainless cleaner

The machine you need is made by "Dynaflux" or "Walter" any welding supply should have info on it.

[illuzion]

Great, thanks I'm really glad someone posted it. Does anyone have experience/opinions as to which is the better unit for the money?
-illuzion

[wrench3047]

There might be a cheaper product. I used to use a polish for my bikes chrome pipes that took off the heat discoloration. I don't know if it would work on stainless but I would give it a try on a scrap piece. Wenol metal polish in the red tube. It's about 8 or 9 dollars a 8 oz tube.

[H80N]

Guys
here is a link to another manufacturer.. do not know them or quality.. as has been said.. not much magic to the power supply but the formulation of the solution is the key..

http://www.screenpro.net/weld.htm

Two Major Cleaning Methods..
in "Passivation" is usually a nitric acid solution
and in "Electropolish" is a witches brew usually consisting of a major part Phosphoric Acid.. somewhere between 10 and 30 percent sulphuric acid... and somewhere around 1 percent nitric acid... using high current densities at low voltage DC...

am not sure what these guys are using.. but is acid based.(according to their ad). may be easier to just buy the prepared solution... do not know...

one huge caution in the stainless weld cleaning area!!! there are some weld cleaning pastes out there that contain a mix of Nitric Acid ,sometimes some Phosphoric or Sulphuric acid and HYDROFLOURIC ACID... WATCH OUT!!!! the HYDROFLOURIC ACID is really bad stuff... if absorbed through the skin..causes burns and can cause bone and skeletal deterioration... bad news...
Before using a PASTE type weld cleaner .. please read the MSDS... and if it contains HYDROFLOURIC ACID... or any other flourine compounds... you might be wise to avoid using it... presently the Australian govt is in the process of banning them...
on a side note... there are "glass etching" pastes out there for the stained glass crafty crowd... some contain the same nasty stuff.. be cautious... please..
here is a link to a safety bulletin from the UK...

http://www.hse.gov.uk/../fod/infodocs/652_1.pdf

take care
Heiti

[H80N]

Weld Cleaning Paste...

Guys

the Electrochemical method of cleaning off weld discoloration seems to be by far the best alternative.. if abrasive methods are not appropriate...

BUT If you must use a paste.. then please read the MSDS for that product.. and if it does indeed contain HYDROFLOURIC Acid.. sometimes just referred to as Hydrogen Flouride... then follow proper safety procedures and remedies.. PELs etc... here is a link to guidlines and precautions..

http://www.ehs.berkeley.edu/pubs/factsheets/40hf.pdf

the only reason that I stress this so strongly is that some of you may be working with these compounds already and not be aware of the risks involved..

Weld Safe... Live Long...

Thanks
Heiti

[HAWK]

Stainless Discoloration
Heh Guys,

Is this what you are talking about on the stainless being discolored after welding?