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Hi Everyone
I am out of ideas with this problem. Everything dichroic I fire shifts colour to the blue end of the spectrum.
I have tried so many times but can't get the dichroic to retain its original colour. Just fired a piece that was rich magenta and its now more blue than anything. I have a lot of blue fired dichro.
Have fired from 760 to 800, different holds.
Has anybody had any success with this and fire so, please, please, can you pass on the secret?

The colour you see face on will not be the colour you get when fired. The colour you get will be closer to the colour you see when you tilt the coating.
If you are trying for a bright blue, good luck doing it consistently as the coating companies produce variations from sheet to sheet.
The only way to keep the colour of Dichroic glass the way it looks face on is to not fire it in a kiln.

You may have already seen this about dichroic from A&A Products or others. There is a test strip near the bottom of the page.

http://www.aaproducts.com/DICHROI-TECHNICAL-INFO.html

You should expect the shift. If you want green, start with yellow. If you want light blue, start with pale green.... Like Kevin said there is variation in coatings from sheet to sheet. There is also variation from firing to firing, location on the kiln shelf, and it goes on and on. If you cap a simple coating like CBS boxes or circles, the coating will go dark. If you don't cap it, you will retain most of the color, depending on how hot you go. If you don't cap the premium colors, some or them will popcorn, especially the really pretty ones (not the blue ones). If you look on the CBS website, you will not see anything about which coatings don't do well with a clear cap and which are more prone to "pop-corning". Finally, if you use etched dichroic from a company like Profusion which primarily uses CBS, you will learn about dark results and popcorn, but with the added premium of the very expensive etching.

Unfortunately for me, the unexpected results are what makes the process interesting. If I got exactly the same result every single time, I would have probably quit a long time ago. These same unpredictable results contribute to frustration and people moving to another craft.

I don't know if they still do it, but both CBS and ATF made sample sets of their colors with a 2x2 piece of each color.
I bought these and cut them in half and fired half. I mounted them together for a sampling of each before and after. Even with these, there is some variation.

Barry

Thank you everyone. I really appreciate the replies and help.
Unfortunately, it seems that getting red is out of the question as there isn't a colour above that to shift down.
I sort of assumed that, after my endless tests, but hoped that someone may have some trick.
Seems like we're all in the same boat as far as dichroic is concerned.

Thanks Kevin. The hint about tilting it I wasn't aware of.
Lynn, I agree, the unpredictability is attractive, but I would just like some results more to the red end of the spectrum.
Barry, I have made some tests, but I think I'll make more.

Red and gold are two problematic colors for dichro.

Several years ago I bout a large amount of scrap from ATF. Included was a small (about 2x4) piece of a dull, ugly reddish dichro. When it fired it became a gorgeous 24kt gold. I sent half the piece to Glenn Brown at ATF and asked if I could buy several sheets. He said they tested and prodded and played with the piece and couldn't figure out how they made it and why it was in the scrap.
I still have the pendant I made from half the piece.
Ah well!!

Best of all when you get a piece of gorgeous dichroic glass people wonder why you want to charge more for it or just like Barry said you don't want to sell it. Everyone assumes in this world that everything comes from a factory and it is produced simply as required. I think the best way to describe the coating process used to create the colours is a bit like Voodoo magic. I would not be surprised to learn that voltage variations from the power grids feeding the coating chambers play a role in the particularly precious pieces.
So now if you don't want to drive yourself crazy trying to replicate a particular glass Never buy anything less than a full sheet at at time.

What Kevin said, Also the color will shift across the same sheet.
The other Jim