restoring mouldy old leather

I'm working with some mouldy old leather and discovered there is a lot of 'interesting' advise on the internet.  I'm pretty sure baking at 500F for 18 hours is going to kill more than jus the mould as will a 2 week soak in soda.  

Normally I would brush off the mould outside with a stiff brush (and wearing a mask and clothes that will go directly in the wash after) then work neatsfoot or mink oil into the leather every night for a few weeks until the leather is happy.  This does the trick beautifully.

But sometimes the leather is older and more fragile or the item has historical or sentimental value.  So I reached out to the local museum and asked what they recommended.  Here's the reply.

The Canadian Conservation Institute has some online resources. You might want to start here: https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/canadian-conservation-institute-notes/removing-mould-leather.html

Another great overall resource I know of is a book by our recently retired textiles conservator, Colleen Wilson. It’s called Tales from the Attic: Practical Advice on Preserving Heirlooms and Collectibles. It is available from our online gift shop at https://shop.royalbcmuseum.bc.ca/product/tales-from-the-attic/

I got the book out from the library and I have to say it's a gem!  Definitely buying my own copy next time I'm in town.  

Thank you for sharing, these are great resources! I live in Portugal where mould is a terrifyingly common problem. Good to know I'm not the only one!

I don't have any of those oils (at least I don't know where to buy them) so I've ben carefully using vaseline instead. It's a good cheap, quick-and-dirty option for anyone low on materials, I believe - but one has to take care when putting in on cotton threads or rubber parts, as it degrades them. So it's a good temporary solution, but one shouldn't use it always, just to quickly save a leather item that is not very sensitive.

When I lived in Florida, every time I took my Sunday shoes out from under the bed these white shoes would be covered in green mold.

I would wash them with Murphy's Oil Soap.

If these had been tanned leather I would have then used beeswax to restore the leather.

We heat the beeswax to melt and use a paint brush to apply the wax to the leather.

Can you describe what kind of leather you are working with?

I do leatherwork and have dealt with this, but I might have different advice depending on what it is.  For example, I have experience primarily with thicker leather for bags, shoes, etc, and I'm not sure what kind of advice to give for leather-bound books .

Typically when leather gets moldy it has to do with the humidity, although well-oiled leather will get less moldy.

If leather is old and brittle, oiling it with just about any oil can help.  I make my own blend of beeswax, olive oil, and essential oil (mostly beeswax but enough olive oil to soften it up) and use that.  If you want to waterproof, that's a different technique.

For most thicker leathers, I would suggest first cleaning it with a damp cloth (not too wet, the water can leave marks) and then giving it a few thorough coatings of oil.  That should not only bring it back to a soft, pliable state but also prevent too much future moold.

Put it in the washing machine with 1 cup of fabric softener and run machine. Leather comes out soft and clean. Hang up to dry

Sorry to hear you have a leather item with historical or sentimental value that has mold growing on it. Sounds like you are aware of the dangers of disturbing mold. It's not just "black mold" that produces mycotoxins. All colors of mold engage in chemical warfare to establish and defend their territory from competing mold and from other attacks/disturbances. Different species produce different toxins that have various levels of ill effects on our health - from essentially no effect up to and including death.

Anne, I was alarmed to learn about your shoes that were constantly growing mold under your bed in Florida. It makes me wonder if the mattress, box spring, or carpet under the bed had mold present. Hopefully it all got left behind.

If someone has had prolonged exposure to mold toxins - which can leach from airborne spores into and contaminate pretty much everything they settle on except metal and glass - they will often become hypersensitive to mold. But they will also suffer from an enormous variety of seemingly unrelated symptoms, which can begin with the first exposure. The longer the exposure, the more severe the symptoms become.

We had to walk away from everything as a result of prolonged exposure to mold toxins that contaminated all our stuff. When I say everything, I mean even sentimentals. The only way I found to preserve paper or leather items that had mold was to put them in a bag in the freezer. This would halt the mold growth until maybe a better solution is discovered. The problem is that whenever they are removed from the freezer condensation will occur which will stimulate more mold growth. But they could possibly be put in the refrigerator to thaw out slowly?