I've been using the henna I have for over a year now and I think I want to try something new. So I emailed Mehandi.com (the site where I buy my henna) with a few questions. This is the email conversation:

From me:
"I use Ancient Sunrise® Sudina Henna batch #071210 and have been using it for a year now. I really love it but... I love how it looks before oxidation, I like the orange tint. If I mix it with Cassia will the orange stay/will I get a more orange shade? And if so, what should be the proportion is henna/cassia?"

From their info email:
"Hello,
Yes, mixing it with about 1/2 cassia, you'll get more orange. You might also try our Yemen Light henna. It also gives orange tones and has a lower percentage of lawsone, so will not oxidize as much and will stay more orange."

After this information I ordered samples of: Ancient Sunrise ® Rajasthani Twilight (2.9% lawsone content, and to be completely free of lead, adulterants, contaminanats and pesticides), Ancient Sunrise® Yemen Light Henna (1.67% natural lawsone content, and is completely free of lead, contaminants, adulterants and pesticides) and Ancient Sunrise® Henna (absolutely pure, flawlessly sifted for the richest deep reds and auburn). I plan on doing strand test with all of these once I receive them. I'm kind of excited to try out a new type of henna. :D