Strange stain in Vandyke, what is happening here?

[Ozzietx]

I just processed a couple of Vandyke prints today, and had a strange stain occur while developing.

The stain went away when I toned the print in gold toner, and everything looks good now.
The first photo is still in the developer. You can see an uneven coloration across the middle of the print.
Did I just need to develop longer?

I am just curious what caused the staining as sometimes I like the native Vandyke brown tone.

See photos.

 

[Tom Taylor]

Last week I processed a Kallitype and pulling the print from the final wash I noticed a large circular stain in the sky area about the size of a fifty cent piece. No stain was on the backside and none had appeared during processing and toning. I hung it to dry after which the stain had disappeared. This was the 2d or 3d time I have had such a stain appear and disappear.

Thomas

 

[ebenostby]

I just processed a couple of Vandyke prints today, and had a strange stain occur while developing.

The stain went away when I toned the print in gold toner, and everything looks good now.
The first photo is still in the developer. You can see an uneven coloration across the middle of the print.
Did I just need to develop longer?

I am just curious what caused the staining as sometimes I like the native Vandyke brown tone.

It looks to me like the coated paper was not uniformly dry. When there's a pocket of dampness in the paper, you'll get a darker, greyish image in the damp area.
It generally disappears (in tone, anyway) after toning, but it may still be slightly denser than the surrounding area.