I have had a stock of Congo Red donated by a friend and recently I bought a new stock from a local Lab supplies shop. The second one is a different kind!
In alkaline solution, it becomes purple and somewhat leaches out stain when a stained section is placed in clean KOH.
Are there different types of Congo Red because I may buy again this time from abroad.
Another point, it is really toxic and carcinogenic? Sometimes my fingers are stained and then I nibble my nails! : blow: