i use clear gloss and have found that hot humid weather ( the really high temperatures we have been getting) can affect it it sort of goes white in places but another coat of gloss can usually sort most of this out when the previous coat its fully dried, and i would guess cold damp air would also affect it so i make sure the room im in is warm and dry ( air not damp like condensation on windows) and stays warm till the gloss has dried so i don't gloss anything in from late afternoon in the winter as the air can become damp as the room cools over night. I make sure the paint is dry usually by leaving it at least two days ( that suits my style of building models anyway ) and give it two light coats by brush over a couple of days making sure each coat is fully dry, if you put it on too thick it can pool in places and go tacky as humbrol clear finds its own level, it is worth looking at humbrols channel on how to use there products there is some good tips on them some might work for you some might not we all have our own way of doing things and what works for us. As for paints i have used it on humbrol acrylics, enamels revell acrylics, enamels and vallejo model air and not had a problem with them affecting the actual paint. hope this point you in a direction that works for you, as for me i just keep trying different things to see what does work and suits me you never really know till you try it paul