I have a very old can of Sears Color Fire crystals. The idea was to shake some on your fireplace logs to add different colors to the flames. The can says it contains copper sulfate, and carries some cautions about contact with the chemical. I’m pretty sure this product predated the EPA. Now I’m wondering if I can use this stuff without poisoning my neighbors with the smoke.
Any ideas?
Copper sulfate is used to give flames and fireworks the blue green color: As with any chemical, toxicity depends on duration of exposure and amount of exposure. For the case you are mentioning, I would guess that the risks to exposing your neighbors is very minimal.
These products are still made. They just recommend not using them on anything but wood, and not to use them in fires that will be used to cook food.
Thank you for your answers. So, I guess it’s safe to use as directed.
I just sent some flame color changing thingies as a gift to someone with an outdoor gas firepit. The pkg said “for use one wood fires” (but not “only”). I went through the reviews on Amazon and many mentioned they work well with gas fires. I was worried about explosions but hadn’t considered the fumes 
Also, I grew up with a gas fireplace in our home and we used this kind of thing all the time. Now I’m kind of concerned.
The reason they recommend wood fires only is not due to safety concerns. Copper sulfate is corrosive to steel, iron, and galvanized pipes, so it could easily corrode the gas pipes and burners in a gas grill or fire pit. It “works” in gas fires to the extent that it makes all the same pretty colors, but at risk of damage.
Thank you for the info. The recipients are pretty smart cookies so will probably read the warnings but I will share this so they can decide if they want to use it or not.
I’d say the biggest risk with an outdoor fire pit is putting in too much, so some of it still remains after the fire is turned off. Add water from rain or heavy dew, and it will start to eat at the pipes. If they do use it, do it sparingly and give it time to burn off.
There may be color changers that are designed to work with a gas fire.
If it says “for wood only”, don’t use them for this.