silver stain problem

[beismann at em.uni-frankfurt.de]

Hello,

I have done silver stains of SDS gels many times before but last time something strange occured: I got an inverse stain with dark background and light protein bands (altogether rather faint). Before this stain, I prepared fresh thiosulfate buffer, and formaldehyde was freshly added to the silver solution and the developing solution.
What can be the cause of the inverse staining, an thus, how can I get back positive stains?

Thanks for helping me,

Silke



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