Wet forming: how much curvature is too much?

[mikesc]

Btw.."cuir bouilli" despite what Wikipedia and other "sources" say..is not the French Translation" of "boiled leather"..Boiled leather is the English translation of the French phrase, the French phrase existed first..The original phrase is French, which was badly written in French ( modern French can be very "contextual", and sometimes quite "pidgin", old French even more so ) and translated to English..The "boil" refers to the bubbles that leather gives of when immersed in water of any temperature ( trapped air )..veg tan leather will do this "bubbling" in cold water or warm water ( veg tan leather is "porous" and the trapped air in the fibres escapes on immersion..However in boiling water , veg tan leather will instantly distort, shrink and be useless..Do not "boil" leather..Do not put it (unformed leather ) into water that is any hotter than you would be comfortable bathing in..and even that is a bit too hot..having formed the leather, you can then immerse it in water at around 55°C** ( depends on the leather ) briefly..when it comes out it's structure ( leather contains collagens, these are often mis-described as "plastic", like in the linked page ) will be altered..and it will be harder..

Best way to know what your leather's "change" temperature is to put small pieces of the leather that you'll be using very briefly ( 5 to 10 seconds max ) into water that is heated, begin with water at 50°c..then raise the temp of the water in 5°C steps until the leather comes out harder ( it gets harder the more it dries out after ) , but not distorted..test ..every time you use "new leather" or leather from a different part of the hide as it varies across a hide.

*Example "kick" is "coup de pied"..literally a "hit of foot".."gust of wind" is a "coup de vent"..a "hit of wind".."coup d'état".."hit of state" etc.

Another example..French "Le cuir pleine fleur"..literally in English.."the leather full flower"..true meaning in English.."full grain leather" ..another English "split"..the French "croûte de cuir"..which literally would be "crust of leather"..which would make you think that you were buying "full grain***" as the crust is usually the outermost layer, whereas a "split" is an inner layer, split from the outer full grain layer..

Translating literally "word for word" , especially from older manuscripts of "contextual" languages is not a good idea at all..that way lie errors and misunderstandings.

There used to be a site ( in French IIRC ) about experiments in "cuir bouilli", I think it is offline now, I'll try to find it, or ( if it is offline) see if the IA has any pages . There may even be translations of it by someone who knew what they were reading.

**those who still work in Fahrenheit can convert it

***grain is the same word in English and French, it came over "intact" from French into English via the Norman ( "northman" ..Vikings ) who inhabited the Northern part of Modern France..William the Conqueror was a Viking descendant..not a Gaul.He had more in common ancestry with us Celts..Dublin being the capital of the Viking world for a long time. Lot of red haired Normans ( like my mate Guy ) lot of red haired Irish, like my athair / dadaí ( btw note where "Dad" and "Daddy" come from, they are Gaeilge words ) .. Irish and Normans were / are a Viking / Celt mix. Dark and or fair /red..Welsh ( more Celt, less Viking) are darker.

Edited September 19, 2019 by mikesc

[Leb]

@mikesc Thank you for the clarification (and for the French lesson!), I think the way you describe the construction (with a "split") makes sense to me. By the way, I have learned the hard way about boiled leather  some time ago, that's why I used "boil" Unless rawhide behaves differently, I don't believe it was truly boiled.

I wish there was a good picture of the inside of the basket - I thought the lower line was just there to hold the brown rim (but I can almost convince myself there is a slight "dent" so it's possible the brown leather covers and holds an inner quarter-sphere leather shape you were describing)

[chrisash]

One thing i have found wet forming is that using a kitchen vacuum machine, by placing the wet leather over a form inside a vacuum bag it appears to me a much better fit around the mould that just placing with a press down mould on its own

If you stop the vacuum just before it completes its cycle, you can really shape the leather through the bag and then continue the vacuum to its limit

[mikesc]

Quote

using a kitchen vacuum machine

I'll bet that goes down a storm with the CFO , unless you have a machine reserved for leather.

[chuck123wapati]

6 hours ago, Matt S said:

Is it possible that the main "basket" is in fact rawhide, rather than fully tanned leather? It looks pale (compare with the edge trim) for a 110-year-old piece of russet veg-tan. The description mentions it being "stiff and hard as plastic" which I would say is a closer description of rawhide than wet-formed veg-tan. I have some very limited experience of working wet rawhide (mostly soaking and flattening dog chews) but the stuff seems far more supple when wet than any tanned leather I've tried to wet-form.

good thoughts indeed I was thinking maybe the leather was made from parts of an animal that already are shaped similar, many cultures used the male genitalia of animals for bags or pouches. 

[Tugadude]

15 minutes ago, chuck123wapati said:

good thoughts indeed I was thinking maybe the leather was made from parts of an animal that already are shaped similar, many cultures used the male genitalia of animals for bags or pouches. 

Actually that is possible.  I posted a seamless dice cup on here a while back and asked folks how it was done.  It was one piece, seamless.  The consensus was that it was  likely made from leather derived from a bull scrotum.

[RockyAussie]

11 hours ago, Leb said:

@RockyAussie Thanks for the tips, I guess the detergent acts to break up the membrane proteins to some extent to make the leather more pliable (and I suppose lubricates the leather to help with pressing?)

The detergent makes the water wet. It allows the water to soak in to the fibres more fully and thus become more supple. Belly leather will give you more stretch for sure and I have seen seamless shoe uppers made from it. What I am saying is that you need to do a lot of stretching and softening before trying to mould to shape. In this post I did awhile back you can see I formed a fairly tight and high handcuff pouch. Note that at the bottom of the top mould there is a relief groove that allows the leather to grip more as the top goes down and give the leather somewhere to swell into and resist back pulling and wrinkles as it dries.

The end result of the waste to cut off on these in the end came down to just over 3/8" (10mm). Too much extra can require bigger wrinkles to try and accommodate and is why @robs456 says to V cut the leather I believe.

[robs456]

9 hours ago, RockyAussie said:

and is why @robs456 says to V cut the leather I believe.

Yes.

[chrisash]

17 hours ago, mikesc said:

I'll bet that goes down a storm with the CFO , unless you have a machine reserved for leather.

Hi Mike

They do not come in contact with the leather, I think the vacuum machines are about £30-50 in the UK see this example

https://www.amazon.co.uk/Automatic-Sealing-Preservation-Starter-Compact/dp/B07NVM339R/ref=asc_df_B07NVM339R/?tag=googshopuk-21&linkCode=df0&hvadid=309920218458&hvpos=1o5&hvnetw=g&hvrand=3907504002454057720&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9044854&hvtargid=pla-680497445189&psc=1

They just suck out the air and seal them up to keep the vacuum also benefit it keeps food fresher and if you freeze them they are a lot more compact (food that is) to store away

[mikesc]

I Know they don't come into contact with the leather Chris, I've got two ( one for me and one fro the kitchen, which although I do the cooking in our house, the CFO still chunters about using "les trucs de la cuisine pour des bricoles".."kitchen things for DIY". I've learned that rational explanation is to no avail, the chuntering may lessen, but the looks and the "roll eyes" do not abate..So..I bought two :)

Co-incidentally , they are on sale again this coming week at our local Lidl..€29.00..I like them, lets me cook and then bag a few portions of "whatever" to go in the freezer for if I'm going to be getting back from somewhere late, I can just phone to say " look in the freezer and in the 3rd drawer down, to the right, you'll find 3 portions of "X" labelled..take them out, defrost them, reheat 2 and don't wait for me to arrive before beginning eating"..Lidl never have enough bags for them when they are on sale, and being French Lidl, the bags are not stocked all year round, and other retailers here charge an arm and a leg for bags..I'm stocking up on various sized bags next week..if they had any bags delivered other than the ones in the box with the machines..I keep thinking that I ought to make a bigger machine ( they are pretty easy ) ..but never got a round to it..Lidl don't sell roundtoits, so I'd have to make one from scratch..if I have enough left.