This directly from AlternativePhotography.com:
"If there is any bleeding of colloidal silver metal, indicated by a red-brown stain running off dense areas of the image, then the paper fibres are failing to trap the tiny silver particles, and it is likely that insufficient Tween has been used, or that the paper is unsuitable. The effects of bleeding may be minimised by processing the print face down, to avoid staining adjacent areas, but there will be some density loss."
and...
"Fix in 2% sodium thiosulphate for 3 minutes.
This removes any traces of insoluble silver salts and, if the print has not already been toned, it partially sulphide-tones and intensifies the image, improving the shadow gradation and shifting the colour from red to brown. (As the bath ages its action in this respect increases). Extended treatment in this bath and exposure to air will result in loss of image density especially in the highlights; it may be used to reduce an overexposed print."