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How to prep metal for torch heat coloring?

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livetooextreme
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How to prep metal for torch heat coloring?

Postby livetooextreme » Wed May 18, 2016 12:16 am

I've been searching the the forms for info on how to prep a metal piece for torch coloring after it has been cut out.

Question is, what type of grinding or flap wheels should I use and what grit fir best heat colors? I know that mill scale needs removed. What kind of torch should I use? Do I needed an oxy acetylene setup or will handheld plumbing torches work?

I plan to add a clear powder coat afterwards. How long do I have to get it powder coated before rust starts forming?

Thanks for any help!

muzza
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Re: How to prep metal for torch heat coloring?

Postby muzza » Wed May 18, 2016 2:18 am

I just use flap discs to get it smooth and shiney, generall finishing on an 80 or 120 if there's one handy.
The more heat you have in the torch, the better it colors within reason but the heat needs to be a controllable flame, not a raging flame that will disperse heat all over the piece or it will have no color range. I use an O/A with a number 10 for getting larger areas colored and add finer details with a number 6. If I'm trying to add something like feathers, I get the whole piece warm and then quickly and smoothly add any details with the number 6. Don't forget the metal colors after you remove the flame so learning where to lift is a big part of it. Put the torch too close to metal or hold it still for too long and you gouge the metal. Also the thinner the metal the easier it colors.
My experience has shown that the plumbers type is next to useless as it takes too long to get the heat where you want it so the color is not as defined and forget about detail work.
As for time to coat, I'd say as soon as possible, technically it starts to rust as soon as the heat is removed.
Murray

livetooextreme
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Re: How to prep metal for torch heat coloring?

Postby livetooextreme » Wed May 18, 2016 10:55 am

Thank you for your suggestions! Also, I was just reading that cold rolled steel should be used and not hot rolled. Is that really the case? If I remove the mill scale from HR will it still work fine for heat coloring? I just bought 5 sheets of HR steel so I hope I can still use it for my purpose.

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ben de lappe
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Re: How to prep metal for torch heat coloring?

Postby ben de lappe » Thu May 19, 2016 9:11 am

I used CR purely for personal reasons. #1 was saving me work/labor. HR will work fine, one just needs to remove 100% of the mill scale. For me this means using a grinding rock to cut through the thick stuff. Followed by a 60 grit flap disc to smooth everything out then polished with an 80 grit disc until satisfied with the bright white finish. Couple of things to remember...keep hand and fingerprints off the steel, don't drip sweat on your polished metal either. I found it beneficial to color asap after polish, and clear asap after coloring.

So be at ease, the 5 sheets of HR will not go to waste. You'll just find out how much you really like to grind :D

Doc Hollywood
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Re: How to prep metal for torch heat coloring?

Postby Doc Hollywood » Mon May 23, 2016 10:47 pm

I'm with Ben on this, i dont have any hr in my shop its such a nightmare to clean. I will say, i did set a sheet of it outside to rust, and it took like 2 years lol!

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steel 35
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Re: How to prep metal for torch heat coloring?

Postby steel 35 » Tue May 24, 2016 9:45 pm

For the HR Muraitic acid is cheaper then the grinding wheels & I like 120 grit for the finnish. CR not in this town!
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livetooextreme
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Re: How to prep metal for torch heat coloring?

Postby livetooextreme » Mon May 30, 2016 1:39 pm

steel 35 wrote:For the HR Muraitic acid is cheaper then the grinding wheels & I like 120 grit for the finnish. CR not in this town!


Thanks for the input. I just got my plasmacam all set up and I made my very first cut today - a 2 in x 2 in square! Woohoo! :lol: Once I get the machine dialed in I'm going to cut out something real and try the heat coloring. I just got some 120 grit flap wheels, muriatic acid, long rubber gloves and a tub. I figured I'll use up these 5 sheets of HR and see if I'll continue with it or try out CR.


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