Generally I have been applying glue using cotton buds and throwing them straight in the bin which, as we all know is a terrible waste.
As an alternative I have just discovered how good silicone is for applying latex glue to anything, including leather. You can apply the wet glue and just wipe the brush off with tissue or rag or if it dries on the brush it simply pulls off leaving a can brush for the next application.
Of course the word brush implies bristles which these don’t have, it is more of a blade.
I got this set from jacksonart.com but there are many other places including the fact that they are included in many ‘face make-up’ application sets where they appear to be cheaper.