Posted by: Lucrece | December 22, 2009

MOL Costrel – Molds and Testing

A while back I posted some photos of a very small Costrel (leather bottle) I’d seen at the Museum of London in October 2009.  I’ve been playing around with some construction ideas for a while and was very pleased when I came across this information in another blog by Leather Working Reverend (hereafter “LWR”)

In the post the author suggests the use of molds to form the costrel’s shape – an idea that really rings true for me.  Trying to form the ends of this tiny costrel by hand would be tricky – and it’s just so much more sensible to use a mold.  I’ve not yet found any 14/15th century proof of mold use, but they used lasts for shoes…why wouldn’t they use a mold for this too?

I really liked LWR’s ideas for molding ribs as well.  In the MOL costrel, the ribs seem more pronounced than the rest of the tooled design; this method appears to be a good candidate for trying to  produce that result.

LWR uses one half of a mould and pushes the leather into the design.  Because mine is so small, I decided to make two halves and clamp them.  Here they are.



  1. Nice work on the costrel! The ribs are nice and clear but as you say shallower than on the original. The rib moulds always end up needing to be twice as deep as you think they should be.
    I think you could avoid the wrinkles and crushed ribs by making the internal part of the body mould narrower than the width at the top of the costrel – admittedly difficult to do on one this small. Clamping from the sides and then finger pressure from inside may be enough. My mould is shown at

    Are you going to do the embossed foliage on one?


  2. Thanks! You think the ribs are too shallow? I’m still mulling that over – Have a look at the second photo in my original post – the MOH one from the top. You can see the profile and the ribs seem to stand out less than you’d expect – it’s odd because they look really “deep” in the views from the front. In the original the ribs are a bit shiney which may make them pop from the textured background. I want to do some tests with samples of the tooling (so yes, I’m going to give the foliage a try!) and with the leather dyed – before I do any more to the mold. The tooling should depress the background even more,so the ribs should be/look more pronounced. I posted a couple more pic: a profile and my mold- tell me what you think.

    Thanks for the mold link too….who do you think I borrowed the design for mine from in the first place :D? I’d done molds like the ones for ends before – but hadn’t any good ideas for the rest. I’m with you on the finger pressure…was thinking something along the same lines.’s too big too. 4.5″x4.5″.

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