RE: Can PU replaces DOPE?
There are at least two kinds of aliphatics. The original, and then the water resistant, such as Titebond type 2. White glue is something else.
Model airplane dope is very similar to dope used on full scale airplanes. Perhaps if there are people building fabric covered airplanes in Hong Kong, you can get some from them. BTW, if you do find dope, it may not be as adhesive as it used to be, though in my experience the stuff for full sized airplanes is much stickier than the stuff for models, and FabTac is REALLY sticky. I have some good dope from Aircraft Spruce, but somehow I doubt they ship to Hong Kong. Remember that nitrate is stickier than butyrate, but nitrate is not fuel proof.