I think it looks like PVA glue residue scrapings. If this is not the case maybe you got the wrong forum
I use the UHU Gluestick... and it is water... based, don't know the therm... but I have a water sprayer and a sponge and from time to time I spray the bed and wipe it even with the sponge... this sames some gluesticks and suspicious withe powder in my bin