Wet forming: how much curvature is too much?

[Leb]

Hi everyone,

I spotted this "leather basket-hilt" in the interwebs https://fencingclassics.wordpress.com/2009/01/08/leather-hilted-singlestick-britain-c-1900/
As far as I can tell, there are no visible stitches going across the hilt. I never tried wet-forming anything so extreme in the past (the closest thing was a flask, where I basically copied what this person did here: https://leatherworkingreverend.wordpress.com/2010/05/06/flackets-the-other-leather-bottle/ ), but thought I'll give it a go.

I made a prototype which is about 10cm tall, and has a top-view profile of an ellipse with major/minor axis of 12 and 10cm respectively. The leather is about 3.5mm thick, and soaked it in room temperature water (maybe I should heat the water a bit more?). When I try forming the leather, I can only get so far before getting stuck due to wrinkles, and I am not sure how to get rid of them without the "cutting triangles" technique. I tried "pre-forming" on a less aggressive shape, but that didn't seem to make a difference. When I had wrinkles on my flask project, I got rid of the wrinkles by using a "multi-step" approach - that is, I would press as much as I could before the wrinkles would prevent me from going further, let the leather dry, resoak, and then press again, which would usually deal with the issue. However, multi-step approach doesn't seem to work here.

I'd like to ask you opinion if you think this should be formable, and whether there are some crucial steps I am missing which prevent me from succeeding. I wonder, if rawhide forms differently to veg tan (perhaps it is possible to "boil" rawhide onto a shape?). I would also be interested in hearing some theories how the hilt in the first link could have been made. Perhaps forming on a half-sphere first, and then squeezing on the sides by hand to make an oval shape could be an approach?





The "top view" size is about 12x10cm (which I suspect is one more problem, I guess it should have less elliptical)

I am only able to form the first ~2inches before I cannot push my press any further with clamps or otherwise.



This is due to wrinkles forming


Now, perhaps I have left just a little bit too much excess leather, however, I wonder if this shape is in general too much for wet forming.

 

[garypl]

Have you thought about wet forming the upper dome section and then stitch the bottom cylinder to the dome?  Don’t know if this design would work for you, but seems it would give you a smooth surface all the way down.

Gary

[mikesc]

On the picture in your 1st link, I can see a stitch line going across the crown of the "dome" starting about 3 or 4 cm to the left ( as we look at the photo ) and slightly below the 9 o'clock position of where the stick enters the hilt..I think that the seam would continue across the crown of the dome and down the other side of the hilt, so that the hilt is maybe wet formed from one piece, but with a "split" which is then sewn up..Inside the dome part of the hilt you could have two hemispherical wet formed parts sewn together, with the seam at 90 degrees to the outer seam.This would be reinforcement.These two hemispherical parts could also continue on down to the wrist..and would incorporate ( via two holes ) the sewn in ends of the stick "tube"..

This stitch line over the crown of the dome part would not be facing many incoming blows, and so would not get damaged..

Edited September 19, 2019 by mikesc

[chrisash]

Your shape does not look the same you have a straight edge from the bell shape , whilst the picture shows the curve continuing into a much more bell shape, I assume the row s of stitching is just to hols on the banding close at the top and inside about a inch or so

Have you tried using Belly which may be more flexible and also some thinner leather and maybe two or more layers deep stuck together, In those days the sailors would have been experts on using leather, so it might have been made like PAPIER MÂCHÉ, small pieces lining around a mould and stuck over each other to build up the thickness and just a micro thin covering over the top

[Leb]

Thank you for the replies everyone.

@garypl stitching another section is certainly something worth considering, thanks.

@mikesc Do you mean these two stitches circled in yellow? Nice spot, I completely missed it, thinking it was just a scratch.
Having only these pictures to go with, I think the construction you describe is certainly possible. However, it still escapes me how the outer "dome" is seemingly made form a single piece of leather.

@chrisash Ah, very good point about the shape. The more gradual shape should help, and I do now see that it is more of a bell rather than an ellipse. Interesting suggestion regarding using very thin leather in multiple layers. I have just quickly thrown a ~ 1.5mm leather (so not that thin) to see what happens, and to my surprise it wrinkled more than the thicker leather. I'll need to try with some 0.8mm goats leather to see what happen. Regarding belly, I will keep this in mind, thank you. So far I have been using scrap pieces (not even sure anymore which parts of the hide are they...)
 

 

 

Edited September 19, 2019 by Leb

[Matt S]

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.

[RockyAussie]

I have not done anything quite with so much stretch and it does say that the leather was boiled which also I have never done. I think your thickness is getting a bit much but for the little it is worth I will say how I would try to do it. Leave the leather soak in hot water with detergent in it for a half hour or more. If you check up on how staking is done in the tanning process you will see a somewhat pointed stick that the hide is repeatedly pulled down over and with a fair bit of effort this can stretch  a hide a lot in any given area. By working the centre outward you should then only need to work on broadening the point out to give you the more dome shape you are wanting. 

[Leb]

@Matt S It does look like rawhide, doesn't it. I think I'll just have to order some rawhide of different thickness and see what happens.

@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?)

Edited September 19, 2019 by Leb

[robs456]

12 hours ago, Leb said:

maybe I should heat the water a bit more?

Yes, definitely. even your link says it's made with boiled leather. Boiling the leather will change the leather (on a molecular level?) and makes it very pliable and will dry hard as, well plastic.

12 hours ago, Leb said:

I can only get so far before getting stuck due to wrinkles

You need to make cuts, as many as you can up to the point the form begins, all around. If that makes sense?

 

[mikesc]

Quote

Do you mean these two stitches circled in yellow? Nice spot, I completely missed it, thinking it was just a scratch.
Having only these pictures to go with, I think the construction you describe is certainly possible. However, it still escapes me how the outer "dome" is seemingly made form a single piece of leather.

Nope :)..I saw those / that line, but I think that is just "damage"..I mean this line ( the arrow points to the line, the line ( fine dark line with a slight curve to it, it goes around "the back"* ) itself is just above the slightly curved line I have drawn in red ) I think this line is a seam ( could be glued onto another "composite" shape underneath as I described above, made from thicker leather ) I think that this "seam" ( I don't think it is a scratch ..Goes right over the "crown" of the dome and down to the edge of the hand guard )..or at least to the edge which is covered by the "binding"..Obviously there is some sort of reinforcement structure under the top cover of thin layer ( the top layer , outer layer, is thinner than you are using, and thus more flexible ) You can see this from the line of stitching which goes right around the circumference of the hand guard about 1cm or so away from the inner edge of the reddish leather binding strip..This "ring" of stitching would be holding the inner heavier leather construction ( two hemispheres on stitched together with a ring of leather around their base ) to the outer "shell"..the outer shell is made from one piece, wet molded, but with a "split across the dome and down the back side which we cannot see..we can only see the "blind" end of that seam..where I have shown..

Made that way..simple

* you might have to "zoom" the image a bit to see the line I'm talking about.

Edited September 19, 2019 by mikesc