An often asked question is what type of glue do you use for Metcalfe and other card kits. I build kits commercially and have tried most types of glue. Probably the worst is standard PVA it takes forever to dry and causes warping.
There are two types of UHU glue one has a petroleum based solvent and the other is water based. The water based one also takes a long time to dry. I used The petroleum based solvent version of UHU for a long time. It sets fast and dries transparent. The biggest problem with UHU is stringing.
More recently I switched to Rocket card glue this sets fast and does not string. However it is expensive at £9.99 for 50ml. Javis make Velo-set PVA this is similar to Rocket glue, but you get more than twice as much for the same price! I now use the Javis product. No stringing and cheaper than Rocket.