Mould making basics for wet forming leather

[UKRay]

Although I have made many wet formed items 'freehand' I have never tried making up a mould and using it to 'mass produce' anything.

I'd like to make some knife cases to fit French made, folding, Opinel knives. Have you ever made up a mould like this or something similar? Got any tips or suggestions? Best of all, could you please post pictures of your moulds so I can get a better idea what is involved in making one.

Will I need to brace the mould to stop it flexing?

What is the best material to use?

How should I clamp my mould? What method/tools/clamps works best?

I saw a thread a while back that mentioned cling-film / sarran wrap. That seemed like a good idea to stop the leather staining but have you got any other good tips?

The radius on the mould edges is concerning me a little. I haven't seen many pictures of moulds and those I have seen have not shown this. I can see it doesn't want to be too sharp but what works best for you?

I'm also keen to see how consistent they will be as I have heard that each leather moulding will need quite a bit of trimming to make it look right.

I'm also keen to know how close to the moulding I can stitch with a machine. There seems little point in hand stitching the things unless I really have to - my idea is to mechanise these processes! I need to know the optimum distance because I think I have to allow for this in my mould design.

Any help gratefully received!

[Randy Cornelius]

Funny you should ask, I have been asked to teach a class on basic case making at the IFLoG show in Indianapolis, In this fall. In that class I will be teaching the basics of making molds for cases. I have used several different materials for molds over the years but I find that wood is the best. It will absorb some of the moisture and help dry the leather while in the mold, thus setting the form you want and keep it. Wooden molds can be made with common wood working tools, the most importaint is a router but with some patients you can make them with wood chistles, rasps and sandpaper. If you can make it to Indianapolis this fall my class will be very afordable.

Randy

[china]

I also use timber to make my molds treated pine, mainly because I have plenty of offcuts, I make an outer shape, the the size of the item + leather thickness and a inner shape, then I soak the leather, and work it into the outer mold the push the inner mold in and hold it there with a G cramp, until it is dry, I always make it oversize to allow for trimming, as for stiching one of my machines can sew right up to an edge as the needle and foot have zero clerance on one side. Hope this helps.

china

[rdb]

There's a book called "The leatherworking handbook", by Valerie Michael, that has some good chapters on 2 piece moldmaking and methods.

I'm not a master of anything, but I have to make molds once in awhile.

I just use my bar clamps and sandwich boarding to hold any molds together. Sometimes I'll make a mold and screw the top right to my old workbench.

If your molds, and leather pieces are consistent, the trimming off of the excess will also be consistent.

As far as radius is concerned, it all depends on your equipment. How close can the foot get to the crease. Holstermakers use specific feet and plates for as close as possible sewing. I don't have those feet yet, so I make do by sewing on the opposite side of the presser foot, and just getting the needle foot as close as it can fit. It just about goes right into the crease. I don't trim until after sewing, so the walking foot still grabs. This works better on small projects, but larger ones show the mistoops. I'm sure those with the proper equipment will tell you the specific/correct plates, and method they use.

Holstermakers also use their presses, and vacuum pumps over molds for larger production purposes. There's several Threads here on those discussions, as I'm sure you've read.

I don't often mold anything much bigger than a holster, or cellphone case, and that's not everyday, so I still use the old fashioned Stohlman type method with just using tacks, for the most part. But I might have 3 or 4 of the project nailed to my working bench, while they dry. With a big enough bench/ tacking board, small production levels can add up quickly. I place the tack right in the crease, and my way of sewing covers the tack holes.

I hope your questions open a big discussion on this. It could be useful to all...

[Jordan]

Dagnabbit rdb you beat me to it. I could not remember where I put my copy so I could post the info. Great book chock full of good stuff.

[rdb]

Not really related, more free form, but this is my bench this morning.....

[UKRay]

I do have a copy of that book - Valerie Michael lives a little way down the road from here and I plan to check out her courses later this year. She does quite a bit with leather moulding I understand. Her work is superb, I've seen an example in the Leather Museum in Walsall.

Sorry Randy but it is just too far to hop over the pond for your course. I'd really like to but...

Thanks, China - any chance of a picture of one of your moulds please?

I do admire the way you work, rdb. I wish I could be that 'freeform' but I'm just too darn orderly to work like that! I'd have to find myself very special bits of wood and keep them just for nailing moulds to. I even have to tidy the bench and hoover up the floor after work most days so it is clean for the following morning. Not quite obsessive, but veeery close! LOL

Badger was telling me about using fibreglass to make moulds the other day. Absolutely fascinating but he tells it better than I can. He apparently uses a pasta cutter to produce 3mm thick clay strips that replicate the space taken by the leather... sadly I only retained the bit about the pasta cutter and not how he uses it! Hopefully he'll jump in here...

[fishguy]

The Al Stohlman case making series of books, which are pretty readily available at Tandy or leather factory have quite a few examples of using plugs and two piece molds.

[rdb]

Crack me up!

Admiring the way I work? I'm a slob!

Somehow in the madness, I make a few things that work. Here's one of those "freeforms" finished up this morning...

Vinegarooned, but no finish yet.

[jbird]

I don't know how it is but I have done a bunch of wet forming some pretty odd shapes to and I do it like you would think inner mold outer mold but I use 1/2 plywood the better stuff used for cabinets works great for sure wish I had some pics but it works nice and so does the old pin up way.

Josh

Edited March 17, 2009 by jbird

[chestercheeto]

Thanks everyone for the tips.I will try a camera case this way someday!

[Jordan]

I have also used cutting board plastic or whatever it is called. Easy to cut and form curves etc. As long as you remember that no part of the item can be larger than the mouth it has to exit through you should be fine. I really like the 3 part wedge type of mold that is in that book used for the belt pouch.

[UKRay]

The big thing about leatherwork for me is doing stuff the way you want to. It doesn't really matter a damn what anyone else says you can still ignore everything and do it your own way. That is what I mean about your way of working rdb. You just do it your way and the results speak for themselves.

(I was going to edit this sentence but laughed so much when I read it again that I have decided to leave it in - what I was meaning to say, rdb, was that your work is original, interesting and practical - nothing derogatory at all! LOL)

This business of moulding is really a hands on, practical, go and do it sort of thing isn't it? No amount of telling can beat the sheer volume of learning you'll get from an hour spent making a mould and using it.

I like the three piece mould idea too. It seems to add a bit of technical wizardry to a process that is otherwise quite mundane. Designing and making a complex shaped bit of wood or plastic (I liked the idea of using cutting board too - I have several hacked up boards that need re-cycling so I'll give them a go) that really works and does a good job gives me far more pleasure than it should... I'm going to enjoy mould making.

Thanks for all the help guys. A quick question on the subject of materials, would you varnish a wooden mould or just leave it plain? Would the varnish help the leather to slide more easily or would it be better to allow the wood to soak up the moisture from the leather?

Edited March 18, 2009 by UKRay

[gtwister09]

Ray,

I have used birch plywood for some molds and I use polyurethane on it to keep the moisture out of the layers of plywood. When I first used those molds, I did not apply a finish to them and they started to delaminate over time. All the later ones definitely had a finish on them.

I also use a lot of used plastic cutting boards. I used to go around and pick up the used ones from various thrift shops and I used them for molds and our initial maul heads (no longer use these for maul heads but I do use stock poly rod for them now). Now a lot of people around give me their used ones and I get a care package every so often of delrin and other plastic cutoffs. If I have a special shape I generally rough cut it on the bandsaw and then use power tools to shape it to its final shape. Nice thing about these is that they don't absorb moisture. You can make an inner and outer mold quite quickly.

Regards,

Ben

P.S. My son broke the keyring portion of his alarm system and we made a piece mold for this one (inner and outer). Total time for mold making , drying, hand stitching, edging and finishing was a hair over three hours. Drying time was the longest factor (almost 1/2 the time). A heat gun would have helped to dry it. He could have spent a little more time on the cutouts but.......

[rdb]

UK, don't worry bout my feelings, they're numb from old age anyways...lol

I know wood patterns and mold/moulds have been used in Leathersmithing forever, but because I can't think normal, I often have alternative ideas.

What seems like a long time ago, in a land far away...I was doing a lot of pottery. The one thing about wet clay, is its forgiveness. I have made many two, and more piece molds from it. It shapes up easier than wood, and can be altered quickly. You can let it dry, throw something over it, and then pack the negative space up with more clay...2 days or so later, you have a mold. Fire it up for a more permanent one. You can take the clay and mold over things for a shape you like...you get the picture. If you make a mistake in the mold, just add more clay. For certain projects, this type of thing is more suitable than spending a long time shaping wood. Matter of fact, I just might make one up later this week...

Ps, you could use concrete, or paper mache in the same manner...

And now, back to your regular programming...

[gtwister09]

rdb,

We have used some of the polymer clay for very weird shaped molds several times and you are correct it works quite well. I haven't tried paper mache but would think that applying a finish over it after it was dry would keep out the moisture.

I never would have considered concrete. When we do concrete countertops and such we build molds or forms for them rather than using them to create a mold....different thought...Uh-oh.

Regards,

Ben

[Trevor]

Hey guys,

I have been making moulded stuff for years now and have managed to sell all of it. It really and simply comes down to the mould itself as to how good your project will turn out. I use some plastic and some wood. When I say wood i mean some cheap almost firewood say pine or any sturdy wood you can lay your hands on and the other is some good sturdy plywood. The plywood is great because it will handle the stress of being pressed or squashed. I will include some photos of the hand made moulds that I use.

I have moulded light chrome and heavy Veg tanned leather. The difference being how much care you take of it during the drying prosess. anyway to start we take the shape of the item that you need to make a pouch for. This can be anything from a watch pouch to a pocket knife ir a small handgun etc etc. It alwys pays to have the item on hand also. This will make life very easy.

Lets start with a pocket knife pouch which is simple and easy to make. Firstly make a shape that is simple and with rounded edges the same size and just bigger than your item. cut and shape the wood (made easier with a sander of some kind) this can be longer than required but must be high enough and wide enouh to house the object. see photo.

You will want the edges to be rounded but not by too much. The base should be flat.

Secondly make the top of the mould. Just look at the picture and you will see what I mean. Now I have used some cutting Nylon board but plywood is the best. Say about Half and inch thick is ideal. The thinner it is the more likely it could break.

The sharp edges that will touch the leather (ie around the inside of the top) need to be smooth because they will mark the leather when pressed.

Will post the rest soon. T

Edited March 19, 2009 by Trevor

[tonyc1]

Many years ago I saw some moulds made from liquid acrylic or such that a hardener was added to to make forms. I never tried it but the bloke reckoned it worked and went hard quick.

Tony.

[UKRay]

You know that feeling when the light suddenly comes on...

Looking at your pictures, Trevor, the whole moulding making process suddenly became easier. Using cutting board to make an external former (because it doesn't flex too much and is easy to shape) makes perfect sense. Building the 'plug' from pine or some other easy to work softwood is a no-brainer.

Sealing the plug makes sense - as does sealing a plywood former to stop de-lamination.

Now what about clamping the bits together?

I've seen all kinds of clamp in my local hardware store - what sort do I need to get? Pictures would really help here as I have a feeling the trans-atlantic tool naming thing might be different - and the brand names aren't the same.

[Jordan]

"C" clamps of a suitable throat size should work fine, for a larger form, extra blocks of wood spanning the distance between the clamps will equalize the pressure. Wax will work to ease removal of leather from the mold. Also those screw in hooks like a cup hook, mounted on an interior block of a mold would help by giving you something to grab onto with pliers to pull it out of a molded item.Quick release carpenters bar clamps will also work.

Edited March 19, 2009 by Jordan

[Bree]

Funny you should ask, I have been asked to teach a class on basic case making at the IFLoG show in Indianapolis, In this fall. In that class I will be teaching the basics of making molds for cases. I have used several different materials for molds over the years but I find that wood is the best. It will absorb some of the moisture and help dry the leather while in the mold, thus setting the form you want and keep it. Wooden molds can be made with common wood working tools, the most importaint is a router but with some patients you can make them with wood chistles, rasps and sandpaper. If you can make it to Indianapolis this fall my class will be very afordable.

Randy

Count me in on your class.

[ShirleyT]

Hi, Ray!

Definitely take Valerie's course on wet moulding since you are in the neighborhood. (They fill up fast.) I attended last May, was worth every penny. Her book is a great start. I left the course with two moulds and a good basic knowledge of how to make them; Valerie's husband Neil teaches the mould-making process. I came home and promptly purchased a Japanese shinto rasp that Neil uses that cuts like butter and makes the curve easy to cut. http://www.japanwoodworker.com/product.asp...p;dept_id=12881

Valerie and Neil are great resources and teachers. Neil also works on historical stuff, does lots of restoration and is an archivist of some sort for the museum at Walsall. Valerie is a gem of a teacher. We've adapted her techniques further to wet-forming lots of our fashion items.

AND THE REST OF YOU - take Randy's course if you can get to Indy! You'll find it a worthwhile investment.

To follow up on some of the comments so far - the mould is most important. Several coats of poly-acrylic or equivalent will seal the plywood (birch) helps limit delamination; C-clamps are great - they have plenty of throat, evenly distribute pressure if you use enough of them, and allow for working with different weights of leather. Cup hook for one-piece forms are an ideal way to pull the form out when dry; I found out the hard way. DO NOT use steel nails to hold leather in place - purchase brass or stainless. The least imperfection in the mould will show up in the final product. After-care of the mould is vital for re-use. We wrap ours idividually in bubble wrap for storage, careful storage. After all the work constructing we don't want to re-make. Marine ply is a good way to go if you are going to re-use the mould many times; it's worth it in the long run. Moulds for gussets are a great way to get tight, sleek fit for stitching as well. 3-part moulds are fun, and easy, for small purses and cases. We've not used fthem or larger pieces; we don't want to put that much leather (and all the hand-stitching) at risk if we've screwed it up. And then there are opportunities with masks...we also do some theatrical and costuming...

Wet-forming is a big part of what we do - we owe it all to Valerie.

Best wishes in the process.

Shirley

[Talfuchre]

Tevor,

THANK you for this. I made the top portion of your mold idea already and have been using it great success.

I had thought of making the blank for the knife (a few of them so I could make many at a time) and I am confirmed in what you have made. NICE!

Thanks,

TF