Sailor

Picture should be on this link

I cut and stamped some wristbands last night from a belly. I've just gone to dye them and they're covered in a white fur. I'm struggling to upload a pic at the moment but will keep trying. I'm pretty sure I've read about white crystals emerging from the leather, but how do I tell what it is? I'm worried it could quite possibly be mould as the leather was stored in my old flat for a couple of months after I was badly flooded on Boxing Day and despite having dehumidifiers on 24/7, I did have problems with mould on the walls, mostly white mould, as well as blue, green and black.

I'm trying to sew something that requires sewing a strip of leather that jumps from being 4 layers thick to 2 layers thick. When the needle gets to the thinner section, the foot is still partially on the thick section (so not pressing hard on the thin bit?) and stitches are skipped until the foot comes off the thick section. I'm guessing this is due to leather moving with the needle. Apart from this little transition section, the stitches are perfect on the rest of the strip, great tension, no skipping. What is the best way to resolve this? I've only had the machine a few months and foot-pressure isn't something I've played with on this machine. So is it as simple as increasing the pressure as much as I can so it squishes it? Or do I need to skive the hell out of it so it's a gradual tapered decrease instead of a big step? Or is there another method? I would usually cut the pieces so it would only step down one layer at a time, but even then it skips one or 2 stitches. I hope all that made sense! I've been lurking on here for a bit anyway, usually searching for questions that I have that have already been answered, but this is my first post, so 'Hi!' Thanks in advance.