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Waterproofing of Leather Boots

 

(a personal view from your chemist secretary)

 

Skin or hide is almost waterproof or animals would leak all over the place, so making waterproof boots should not be a problem.  However tanning of hides to produce leather is necessary to remove putrescible (stinky!) components.  Many of these are the lipids (fats) which make hide waterproof and what remains as leather is mainly dense twisted protein fibres.  Lipids are hydrophobic (they hate water – think oil, PTFE etc) whereas proteins are hydrophilic (they like water).  The methods of boot leather tanning and its thickness do overcome a lot of the water permeability problem but it is worth helping out particularly when your boot leather is well used.  In my early days of walking, the boot waterproofing of choice was neatsfoot oil, made from the feet and shinbones of cattle because it remained fluid down at the low ambient winter temperatures of the lower parts of the animal.  It softened the boot leather which was a good comfort point with the stiffer leathers then used.  However it could oversoften – one pair of my walking boots ended up like a pair of carpet slippers.  Neatsfoot oil is still used for treatment of horse tack but modern oils tend to be blended with mineral oils which can attack stitching.  Logic would indicate that applying oil or grease would bring back hydrophobicity and so they do as you can see the water ‘beading’ on the surface after treatment with shoe polish, dubbin, leder gris or Hydrobloc (by Zamberlan).  But I find that their effect wears off very quickly. 

 

Now to my main point: when it first came out I was very sceptical of the use of water-based products, such as Nikwax aqueous wax (NAW), for proofing – it seemed counterintuitive to introduce water into the leather.  But I did try it and the effects do seem to last longer that the topical waxy products.  NAW is a suspension of wax in water (rather like milk) presumably held there by a little detergent.  This means that the product, being hydrophilic, can enter the leather surface and carry a limited quantity of the hydrophobic wax actually into the body of the leather which is neater than neatsfoot!  There is a competing penetrative product from Grangers which is formulated from fluorinated polymers (like non-stick saucepans) but when I tried it it seemed to use organic solvents and left the leather rather dry.  So I rate NAW in personal use and as a chemist.  It comes in a 125 ml plastic bottle with a foam pad applicator on top and (another advantage) it can be used on damp leather.  The foam pad is a bit rubbish as if it contacts a lacing cleat on the boot a few times it falls to bits.  I use the applicator only to pat on blobs of the product evenly over the boot and then use the same coarse rag (corduroy actually) each time to immediately smear the Nikwax over the leather especially into the bend of the ‘toe joint’ where cracking occurs first.

 

Note that the Nikwax company are bringing out a new water-based Waterproofing Wax for Leather this year but I haven’t seen or used it yet – maybe they’ll send me some to test!  Note also that I have no connection with Nikwax except as a user, but I did get some free Grangers proofer a while ago from Cotswold. 

 

 

Brian Brough

May 2009