Heather can't answer about glyoxal because I haven't used it before. I was sizing with gelatin and hardening with formalin. I was adding formalin directly to the gelatin solution (0.2ml formalin per g of gelatin) then discard unused solution later - this is much quicker than sizing and hardening in separate steps and uses a lot less toxic substance. But then I started to size with PVA, it's very quick, non-toxic and effective. I use a locally available PVA glue for sizing, diluting it by 1+2 to 1+5 depending on the needed effect. There's a special PVA sizing available to printers in the States; it's Gamblin PVA size. It can be used full strength or diluted and I know several alt process printers who prefer this over the old gelatin sizing method. For which process you need to size the paper and which paper is that?