Purpose of sulfosalicylic acid in Ponceau? - (Jun/04/2004 )

Hey,

I'm going to do some Ponceau staining and I've found recipes for stain with and without sulfosalicylic acid. I was wondering what the purpose of this chemical is in the stain ... does the absence or prescence depend on what type of membrane is to be stained?

Your help/knowledge is greatly appreciated...

Thanks,

Sulfosalicylic acid usually used to precipitate the proteins