Is there expiration date for Malachite Green?

[tiger15]

I am using an old bottle, must be over 10 year old. There is no expiration date in the label. If it turns the water green, does it mean it is still effective.

 

[Redshark1]

I have used a bottle that was 25 years old and the medication worked fine.

It is a stable dye.

However, I am a scrap metal dealer and know that gold does expire.

Send your old gold to me and I will dispose of it in an environmentally safe way free of charge.

 

[kno4te]

Old thread brought back to life. Just in time for Halloween! New bottles have an expiration date now.

 

[duanes]

Malachite green is a kind of organic dye, that beside turning things greenish, is anti fungal, anti protozoal, and anti bacterial.
It may have gotten more concentrated over the years, but not overly if closed tightly.
Used as directed it is toxic to aquarium parasites like ick, and fungal infections.
It is considered a carcinogen, so probably best not to get significant amounts on your skin.