Just as pallets are incredibly useful, so too is 'pallet wrap' - a very thin, transparent and incredibly strong plastic film supplied on rolls which is both stretchy and self adhesive. Other than a pallet itself - surely there is no other product with such useful qualities? The number of possible uses is endless, but helping stack firewood must be somewhere near the top of the list.
Why do we need pallet wrap and why do we need to stack firewood at all?
First of all, firewood needs to be stored somewhere dry, preferably for about 2 years, so that most of the moisture within the wood is evaporated or else much of the precious carbon energy locked in the wood is wasted by evaporating large quantities of water in the fire itself. Check out 'The latent heat of evaporation of water'.
Secondly, stacking wood saves space and thirdly, pallet wrap stops our stack from collapsing and provides extra heat from the 'Greenhouse' effect of using translucent film.
We could just throw our precious logs onto the ground and cover them with a tarpaulin, but this has many problems:
I stack my logs on pallets to keep them off the ground and help with ventilation - some air can circulate under the log stack. I also create special vents in the pallet wrap to help evaporate the water..
But let's just go back in time a bit to last year when I wanted to stack my firewood on a pallet to dry. The middle of Summer is the best time to do this job as it gives the wood, which was cut the previous winter, enough time to dry for the forthcoming winters.
So, I was dutifully stacking my wood thinking what a nice pleasant and easy job it was and after getting to about 1 metre (3 feet) high ........ One of the corners of the stack spontaneously collapsed and I literally had to rebuild the whole thing from scratch - DOH!
Stacking wood is a lot easier against a wall or in a shed where you have upright surfaces to lean it against, but my stacks need to be free standing like in the photo above. Anyway, after rebuilding the structure 3 more times, I realised that I had to give the whole task a great deal more thought and consideration before the next build.
The log stack is ventilated by a combination of natural ambient wind and hot air convection currents induced by the 'Greenhouse Effect' within the stack.
When the sun is shining, convection currents occur as expanding hot air requires an escape route. If the sun is in the west, then the west facing sides of the stack get warm - up to 40 degrees C so far. The hot air expands and rises and this movement sets up a circular current inside the stack which results in air moving downwards on the colder East side of the stack and out of the vents.
The simulation above assumes that the wind and sunshine is coming from the same direction. The air comes in from the vents and under the pallet on the left hand side and rises up into the top of the stack by convection currents and comes down again and out of the vents again. The graphs at the 'Graphs' step confirm that air is moving fairly freely, even deep within the stack, by showing constant temperature and humidity changes on the probe located therein.
If the humidity in the centre of the stack was a constant 100% and the temperature never changed much, then the conclusion would be that there was no air circulation and inevitably our logs would turn to compost.