Members Eelco Posted February 1 Author Members Report Posted February 1 30 minutes ago, chuck123wapati said: it sounds like you want to make a double-sole moccasin. or maybe a Roman Crepida. already beeen done lol. Google seems to have a hard time deciding on what a Crepida is exactly; but the term has led me to some other interesting historical designs. The term calceus seems to come pretty close to what im thinking of. Great that its already been done; not trying to win any originality points; I just want a shoe that will hold up to hours of indoor walking, while looking good in the process. In a perfect world id both find the time to give a decent shot at doing it myself; and find someone capable of executing on it professionally. The more theyd have done it before the better. Quote
Members Eelco Posted February 1 Author Members Report Posted February 1 58 minutes ago, chuck123wapati said: soaking your shoes in acetone wont be a good thing Im hearing mixed things about it; depends on the timing and type of leather I guess. But the melting point of the PVB + plasticizer can be tuned to be super low, like 50C or so; plus water also acts like a further plasticizer on PVB. So if you just soak the leather outsole in warm water, I think you could just tear it right off with a bit of force, without meaningful heat exposure to your upper. Quote
CFM chuck123wapati Posted February 1 CFM Report Posted February 1 15 minutes ago, Eelco said: Im hearing mixed things about it; depends on the timing and type of leather I guess. But the melting point of the PVB + plasticizer can be tuned to be super low, like 50C or so; plus water also acts like a further plasticizer on PVB. So if you just soak the leather outsole in warm water, I think you could just tear it right off with a bit of force, without meaningful heat exposure to your upper. it's highly flammable and very dangerous to inhale who cares about the leather think safety. not to mention the quantity you would need, simply not worth the potential problems. A crepida is a light shoe. Good luck. Quote Worked in a prison for 30 years if I aint shiny every time I comment its no big deal, I just don't wave pompoms. “I won’t be wronged, I won’t be insulted, and I won’t be laid a hand on. I don’t do these things to other people, and I require the same from them.” THE DUKE!
Members Eelco Posted February 1 Author Members Report Posted February 1 15 minutes ago, chuck123wapati said: it's highly flammable and very dangerous to inhale who cares about the leather think safety. not to mention the quantity you would need, simply not worth the potential problems. A crepida is a light shoe. Good luck. Acetone isnt all that different from ethanol in its toxicology. And I frequently handle both by the gallon. Not taking any baths in it though; and proper ventilation never hurts. Seems like these would be the least of my VOC-worries as a leatherworker though. I personally dont let any chloro-anything into my house; or any glue with an unspecific solvent composition; so its not like im not paranoid about these things. But yeah I acetone ethanol propanol and ethyl-acetate... those are the only ones I allow into my house really. But to each his own. Quote
Members Eelco Posted February 1 Author Members Report Posted February 1 Found some numerical values for water permeability of PVAoh here in Figure 76 and some values for leather here. To put that in perspective, even 20mu of the most water permeable glue I can think of, has a 10x greater barrier to moisture than the most permeable leathers; and is kinda on par with a less permeable leather. So I think that pretty much proves that if you care about permeability, you better stay away from linings at all and stick with the single layer leather; and also if you want your sole to contribute, it better be a single layer. Also a single male foot thats active can produce some 20g of sweat per hour. Even with a leather shoe on the more permeable side of things, like a single layer thin mocasin, itd only barely keep up. Thats of course not taking into account the ability of your leather to store/buffer moisture; not like im going to be working out 8 hours continuously. But yeah... stay away from glue if you care about moisture, seems indeed like it should be the moral of the story here, at least if im reading these numbers correctly. Not super happy with that conclusion because I kinda like the idea of replaceable outsoles; but perhaps only glueing the outer rim of an outsole with a strong cement would suffice? Also it is quite possible I am not reading these numbers correctly. If you take a thin layer of permeable glue and squeeze it out as much as possible, you dont get a homogenous 20mu line, but rather a variable thickness with both sides of the leather in near contact in many places. So what the net resistance of such a glue line is can really only be established empirically I think; not hard to imagine that in practice things could be an order of magnitude better; in which case properly applied glue would be back on the menu as a viable option... Quote
Members dikman Posted February 1 Members Report Posted February 1 After reading all this my brains hurt......... Quote Machines wot I have - Singer 51W59; Singer 331K4; Seiko STH-8BLD; Pfaff 335; CB4500. Chinese shoe patcher; Singer 201K (old hand crank)
Members Beehive Posted February 1 Members Report Posted February 1 Hey, I gotta glue here in a bit. Weldwood glue. Takes two coats 15minutes apart. Roll the edge and leave it alone until tomorrow. Trim, groove, stitch. If you store the small can of Weldwood inside a plastic peanut butter jar. It'll last longer. If 3M weatherstrip glue wasn't Yellow. 3M #90 spray adhesive? You bet it'll do. Quote
Members Eelco Posted February 2 Author Members Report Posted February 2 Thinking more about it, I think the most practical method would be a premade thin glue sheet, with tiny say 0.1mm holes punched through in a dense pattern. You could set up a simple desktop laser cutter to do that in the absence of an off the shelf product. PVB would be a nice base material since you could either melt it on with a heatgun or mist on some ethanol to activate it (not many other materials that are top-tier adhesives, match the mechanical properties of leather, can be hot melted and are soluable in a bunch of eco-friendly solvents; but not in water; infact I think only PVB fits the bill). If you get the hole pattern right it should add minimal moisture resistance to the total of your shoe. The total effective extra length that the moisture needs to travel through the leather should be on the order of the hole spacing; a few ten's of a mm or so. It should easily be strong enough to bond linings to outers; and maybe also leather outsoles; but again if you add a rim of a proven shoe cement on the outside it should be totally fine I imagine. Quote
Members Eelco Posted February 7 Author Members Report Posted February 7 https://www.hotmeltstyle.com/eva-hot-melt-adhesive-web-film-product/ https://www.shanghaixinxu2016.com/product/honeycomb-holes Found two hot melt films specifically made for this purpose. EVA isnt breathable itself but that does not matter much when its perforated. Quote
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