HOW TO WORK HIDES IN THE HEAT
This month's tip comes from several people this summer, who were each encountering a different challenge with summer heat. And so:
HOW TO WORK HIDES IN THE HEAT
Read on.
Know the terrain
First let's get to know the dangers + challenges that high heat can bring.
1. Bacteria
In tandem with moisture, high heat can cause our wet hides to degrade at a much faster rate than they do in cool temps. If your hide is in a low-tannin bark liquor you may suddenly find a massive bloom of mould and a weakened hide underneath; or if it's in a de-bucking solution, you may have a very stinky hide within a day (when normally you can leave it for a week).
The above scenarios indicate the presence of collagenases - enzymes produced by bacteria that break down collagen. These bacteria are more highly active at temperatures we humans consider high, ie 25 to 40 degrees C. One hide-eating bacteria genus is Bacillus, the same type that we harness when drenching bark-tanned leather. Bacillus bacteria are mesophillic (they love moderate temps, which we feel as hot) and have peak activity at 37 degrees C.
In other words: right as temperatures soar + you start feeling feeling the heat, hide-eating bacteria are most active.
2. Drying out
Daytime heat can cause your hide to dry out before you're brought it to the next stage. This can range from frustrating to sabotaging. One the more minor end, a hide may dry into stiff rawhide before you've framed it or softened it; on the more extreme end, a thin hide can become so paper-like if it dries quickly that it completely rips apart.
3. Singeing
Hides are proteins, and proteins can be cooked. With the addition of oil and water, a hide in direct sunlight on a hot day can quite literally be cooked or singed in front of your eyes. The hot spot will rip and dissolve. Every species has a different innate resilience to heat. In my experience, sheepskins are the most prone to singeing.
4. Heat exhaustion (in the tanner)
Don't forget about this one! Summer is precious, at least where I live. We get a short break from the rain we love to be outside tanning as much as possible. But it's easy to overdo it hurt ourselves - and our hides - with heat exhaustion.
How to handle it
Okay, now let's do some preventive hide medicine:
1. Bacteria
Speed up your usual buffer times. What's play for one week in the fall may be okay for one day in the summer. Make fresh bark liquor batches sooner; trust that hides are ready for their next step sooner.
Keep wet hides in the shade or in a fridge at pause points
2. Drying out
Apply cool wet towels to hides during framing to keep the hide moist + pliable
Pre-smoke thin hides to prevent their tendency to rip apart when softening
Any hide that dries on you before you're done softening? Smoke it, and soften again.
3. Singeing
Avoid direct sunlight with untanned hides, especially as you apply fat emulsion
Plan your evenings + mornings
3. Heat exhaustion (in the tanner)
You know these: drink more water than you think you need; wear pale linen shirts; take breaks in the river or ocean
Also: eat flavonoid-rich fruits, berries and watermelons
Last but not least, practice Fire Hours
All of the above can be mitigated by tanning hides in the mornings and evenings. When I worked in the bush, we called this “fire hours.” It's when the whole backcountry shuts down between 12pm-4pm in British Columbia during forest fire season. The chances of vehicles or a crew accidentally igniting a fire or getting stuck behind a fire are too great. So everyone who works outdoors gets up at 2am or 3am, works for a bit, and then comes home before noon. Some crews go out again in the evening.
I did Fire Hours two summers ago in the 2023 heat wave. I spent my afternoons at the ocean with my dog (I do not live with air conditioning, so we were always outside); my mornings and evenings were spent at the tannery