Bespoke Shoes Unlaced – a shoemaker's blog

Friday, 10 February 2012

Gum Tragacanth

Another week , another exciting slice of shoemaking life.

It started off brilliantly with a great Eclectibles page in  How To Spend It in the Weekend Financial Times which featured our brown, Go Faster Stripe lizard shoes. They looked fantastic and we're included on the Contents page and website as well. So a great big thank you to Philippa Clark who puts the feature together

And so to shoemaking, specifically finishing the soles and top pieces. With a black finish, there is no ambiguity - you simply apply black ink, polish, burnish.

But if you want a natural finish, then you have to work a bit harder.

When we were apprentices, our master, Paul Wilson, used to use a solution what he called Gum Dragon. This was applied directly to the sanded sole before you applied the polish. It has the effect of hardening the sole, so that when you apply the polish, it does not go smeary and uneven. After we finished our apprenticeships, we did not have the recipe to make it, so we simply used water instead. This has a similar, but inferior effect.

So I decided to sort it out and get some Gum Tragacanth, as it is more correctly called. And where did I find it? Our good friends at Cornelissen of course, where else?




But buying the stuff was the easy bit. Next I had to find a way to prepare the solution, so I turned to one of our shoemaking bibles, The Shoe Finishers' Guide by W D John, a marvellous book published in 1934.


And here is what it said about Gum Tragacanth.

It is a gummy mass which exudes from a shrub found in Greece, Turkey, Syria, Iran and Kurdistan. The stems are cut and the gum comes out and hardens into flakes or lumps. This is then collected 3 to 4 days later and sorted into grades. The type of cut on the stems determines the kind of gum collected.

It is chiefly used in the manufacture of confectionery and medicines, but just a little is available for the likes of us.

It resembles dry horn or nail and comes in dull off-white contorted flakes which tend to powder over time.

When it comes into contact with water, it swells enormously and absorbs forty times its weight in water. The resulting mucilage is fairly revolting and consists of two parts - a slimy opaque jelly like liquid and a solid part called bassorin which can be filtered out.

The recipe we used was the following

3ozs gum tragacanth to 1 UK gallon of water, mixed and left over the weekend. Filtered and finished with 7ml of 40% formaldehyde. A word of warning though. Formaldehyde is nasty toxic stuff, so you must wear protective gloves and use it outside to avoid breathing it in. DANGER!

1 UK gallon of water

The resulting mixture separates into two parts, the liquid on the bottom and the solid bassorin on the top.





We then filtered out the bassorin.



We added the formaldehyde outside with gloves on using a syringe, and stored it. We have enough for a lot of shoes. I have a feeling it might be a bit thick, so I will test it out and might have to dilute it a bit with water.




And that is that. We have not tried it yet, but are expecting natural soles with the cleanest, smoothest, most even finish you can hope for.

When we have a newly finished sole to compare with an old one, I will post some pictures - I got a bit excited about this, so had to share it with you before having a 'before and after' shot to show you. But it will be here shortly, never fear.

And that, as they say, is a wrap.

Guess what we are going to write about in next week's post? Let's just say that Johnny Depp will be looking over his shoulder soon enough.

Until next week, happy shoemaking!

8 comments:

DWFII said...

James,

I was waiting for this "lesson."

Here in the States we can buy Gum Dragon already made up and filtered. I think it is Thornton who says that you can mix it with a little powdered dye and use it as a finish for natural foreparts. The thing I haven't seen is a water soluble leather dye suitable for mixing in with the GT.

I have mixed it with burnishing ink and that seems to work fine although controlling the colour when starting with a dk.brown ink is a little problematic.

With what I have come up with, however, it is not a given that it will go on evenly and not be darker in one area or another. There's something I am either missing or doing incorrectly, I'm sure.

Waiting eagerly to the next installment when you put your homebrew to the test.

Ian M said...

As you say, formaldehyde is truly nasty stuff. I suspect its presence in this recipe is to act as a preservative, and as such there are many safer replacements for it. I'd tend to look for an alternative if it was me preparing this. A more technical approach would be to use one of the many preservatives we see everyday in cosmetic preparations such as parabens, benzalkonium chloride (zoflora) or chlorhexadine gluconate (hibiscrub). If one prefers a more natural approach, one of the commercially available pre-made gum tragacanth solutions uses camphor as the preservative which has the added advantage of smelling nice.

You might, in some parts of the world, fall foul of regulations limiting the levels of free formaldehyde in clothing (which range between 10 and 300 ppm where there are statutory limits imposed). Bear in mind that some leather tanning agents (particularly re-tans) already contain some formaldehyde so you'll be adding to the levels already in the leather.

Andre said...

I'm quite sure that you will fall foul with the level of formaldehyde allowed in leather with the EU regulations. The level of allowed formaldehyde got reduced dramatically in the last years, so that we have almost stopped it at all, because the allowed level was so low, that almost for no product it was of much use and we still had the headache of might crossing the line. As much I personally appreciate your cocktail, and practically speaking as long your children or customers not biting the sole, there is no problem, you might consider giving a sole for testing and might look out for a substitute. Anyhow as always, appreciate your effort, regards
Andre

jimmyshoe said...

Agreed it is a very nasty substance, and I would like an alternative if it won't damage the gum tragacanth. Are the things you mention going to react with the gum?
However, the solution is dilute and is only used in a very thin coat on the surface of the sole which will be worn off when the shoes are worn in the street.
Maybe I should mix a few alternatives and see how they work.
Thanks for the comments. Best, jimmyshoe

Andre said...

This "very thin code" is what can create the trouble. Of course it's been worn off, but the "reason" for the strict regulations for Formaldehyde is major to protect children who could bite the sole. I know it sounds funny, but this is the info I got. However, the problem with Formaldehyde is known with all the leather chemical companies. I'm convinced, if you call up the nearest lab of BAYER, STAHL etc. and tell them your problem, for sure they should be able to assist you.

damaclese2 said...

i believe the use of formaldehyde is strictly band in the US

Brenda MacNeil said...

I'm wondering where one could find 'The shoe Finishers' Guide'?

Thanks.

jimmyshoe said...

Very good question. We got ours from a library sale which was closing down. You will only find it second hand as it is no longer in print. Good luck, jimmyshoe