May and June is the season to gather bark! I use willow bark for plaited baskets and twining and the process described below is for this use, not for cordage fibres which involves different soaking and preparation.
This is my third year harvesting willow bark, and I think I've learnt a lot since my first attempts which I'd love to share with you.
If you know about coppicing, you will know that certain species of tree, if cut when the sap is low in the winter, will grow back where cut in multiple stems. Unfortunately, in order to harvest willow bark, we must do it while the sap is rising (you can actually do it when the sap is low, but it involves a lengthy process of heating the branch over fire to loosen it!). Once the sap is rising and the tree is in leaf, the cut stem is unlikely to grow back, although willows are hardy trees and a few of the stems I've previously cut in late Spring have sprouted a little. Willow is in never ending supply where I live, so selecting out the occasional young tree is not the end of the world, but you can choose a stem from a previously pollarded or coppiced tree like the one below, which will allow the rest of the tree to live. Choosing overgrown coppice stems also means a straighter piece of wood with less side shoots, which is definitely what we want!
Below is another couple of stems I chose from an un-coppiced tree. Willows are often self-coppicing, or grow with natural multiple trunks, and I chose this tree for this reason. It was also growing long and straight due to the density of the tree cover where I found it. Density can mean a greater likelihood the stem is going to get 'hung up' in the canopy in a tangle with other branches however, so it's worth checking this first:
Both the trees I chose were about 3-4 inches in diameter. Any thinner than this and I find the bark too easy to tear at later stages of processing. Any thicker and the outer bark is hard to slice through and remove.
It goes without saying to get permission from the landowner before cutting anything down, but also remember to check for nesting birds at this time of year. When cutting also be careful to use proper saw cuts even when the trees are this small- a little tree can still kick back in your face, or hurt you if it falls wrong! Providing a clean cut without tearing also prevents the tree becoming diseased. For a quick how to look here (https://www.conservationhandbooks.com/how-coppice-trees/)
Next you've got to lug your stems to where you want to process the bark, which is much easier to do if you remove the upper branchy bits first. Once you've got it home, you've got to act fairly fast- don't leave it more than a couple of days or it will dry out and be very difficult to process.
Some people use a clamp to hold the branch in place, but I just rest it between two rocks and raise it up a bit off the ground. I then use a sharp knife (Mine is an Opinel) and a straight edge to score along the bark. where there are lumps and bumps in the bark such as where small branches were, I cut around these.
The fun part comes next! Using a butter knife I (very carefully!)prise open the slit the first couple of centimetres or so on each side. Anymore than this with the knife and you run the risk of slitting through the bark. I then swap to a bendy plastic pallet knife like the one below:
I then work my way along the whole length of the stem, prising the bark off slowly, until I have worked around the whole circumference and the whole length. The bark should then slip off like a sleeve! This is a magical moment. I love the smell of the salicylic acid and recommend a wee lick of the inside of the bark- it tastes really sweet, and is definitely good for you, being the key ingredient in aspirin!
What you do next depends on what you want to use the bark for! You can use it straight away for plaited baskets, but especially if leaving the outer bark on, it can curl and shrink dramatically. I have tried removing the outer bark immediately using a sharp knife before storing it, but find that leaving the outer bark on allows the tanins to leach through to the bark slowly, giving it a lovely amber colour.
To store the bark I cut it into manageable strips using sharp scissors (around 3 inches wide) and roll it up to store. You do this by ensuring the outer bark is on the inside of the coil, or the edges will curl in and the bark runs the risk of badly splitting due to the outer and inner shrinking at different speeds. You must also keep the coils loose, or they can become mouldy ( I learnt this the hard way!)
When time to use the bark, I soak it in hot water for several hours. This deepens the colour, and allows the outer bark to peel off more easily with the aid of a knife. This can be tricky, and I have ruined lots of bark strips by cutting too deep at this stage. Carefully and slowly is best! I then cut the strips into equal width usable pieces. Willow bark also has natural striations, which often crack when drying, so to some extent the strips you cut will be dicated by where these natural slits occur. I don't know if this is the case with all species of willow or other trees, but its definitely the case with the willow I have here!
I then soak the pieces again and repeatedly wet them while working to keep them pliable. When wet they almost feel like leather, but when dry they are stiff and easy to crack.
Below is a picture of the little pouch I am working on with willow bark from last years harvest! It has a plaited bottom and twined sides.