Tried the Gum Tagacanth , but did not like it much . Either using Saddle Soap with some elbow grease or edge dressing worked best for me . As for a backing of leather , I found that Saddle Butter was better , ecspecially for holsters with or with out lining . Using smooth leather verse cow split ( suede as most call it ) for lining . Smooth leather kept cleaner for the weapon as it did not trap dirt as much .
On the Shoe Stretch subject , the reason I mentioned to go to the local cobbler to obtain is because the Shoe Stretch they use is more reliable than off the shelf products . I've ran out of and needed some fast and I purchased the Shoe Stretch from off the shelf and it sucked . Even though it was made by the same company , they do not sale the good stuff to the little people . Beleive me there is a difference . Just like the contact cement , can't get the good stuff at Lowes or Home Depot .
I use the Feibings brand for Shoe Stretch and never had a problem with it . Use just enough to do the job , if one is worried about dis-coloration , even on the light colored leather .
To give a back-ground of myself , I apprenteinced under Rob Roy originally out of El Paso , Texas . I started out washing saddles , then to minor repairs . Then to building them . As well as holsters , belts , chaps , cases , harnesses , tooling leather and etc...... . Also doing Boot and Shoe repair and Silversmithing . He taught me the old fashion way before he showed me the short-cuts if any . I cursed him for that sometimes , but it did me more good in the long run .
I eventually moved here to NC and continued the leatherwork . Had more work I could shake a stick at . But the Marines needed me worse to make nylon gear . I miss the leather work alot , but nylon work moves quicker . Besides that , not to many people want to pay for honest to goodness custom leather work in this part of the neighborhood if you know what I mean . I still have my tools and sometimes think about selling them . If I do , that means it will be hard to turn back to leather work .