DSF

I did a mug this morning, it came out fine. Left the fan to cool and brought it in to the customer and I noticed a in the white where I had not printed a shade of black, (very faint had appeared) it look when you wash something white and left a dark sock or something and faded marks appear. There was no black or blue on the outside on the image that I did, but the middle does have dark blue. Can the blue seep the mugs and appear on the white. It did look like some that was discoloured and seep out, not all over but near the images. Any ideas why. Or can this happen. Did another mug no problems.

probably there is an ink stain on the inside of your blanket that has bled through the paper.
you may need to line the clamp with plain paper for a few uses to clean in away.

Would have to see a photo to be certain but does sound like the bleed you can get now and then with certain designs. I know many use fans to cool but this isn't instant. It might take 30 seconds or more before it gets below the temperature where sublimation stops. We always dunk in tepid water if it's a design that bleeds into white.

Could also be transfer from another mug if you left 2 mugs cool touching each other.

It was a solo mug, but I'm going to clean the clamp now before that happens again
Thanks everybody