A 5 gallon Paint sticks works fine, but wider is better. I used 5 gal paint stick to experiment with paste, worked great. Cut some ¼ in hard board or MDF to 3 in width and about 16 inches for a 12 in paddle. Leave enough room to hold it down on the bench or table. Some rubber drawer liner glued to the back helps hold it in place.

What kind of glue did you use? If it is water based, water will get it off. Read the label, WD40 will get most solvent glues off. It is also great for sticky tape and label residue removal.

I use yellow wood glue. All it does is hold it to the leather, does not have to be super strong. Paint it on with a brush go easy at the edges so it will not squeeze out much.