After using pruning tools, such as secateurs, loppers, hedge hedge and pruning saws, it’s important to clean them to prevent rusting, and to avoid spreading diseases from tree to tree.
It’s a good idea to sterilise pruning tools after use, especially before using them on another tree or plant. This is done spraying them with alcohol, that is at least 70% in concentration, and wiping them down.
Methylated spirits contains a minimum of 95% ethanol alcohol, and commercial grade isopropyl alcohol from paint stores contains 99.97% alcohol. These can be diluted to approximately 75% alcohol by mixing 750ml of alcohol with 25% water, to make 1 litre of solution. Basically, just mix 3/4 (3-parts) alcohol with 1/4 (1-part) water.
Quite often, wiping down with alcohol will be sufficient to clean off any residual sap from pruning tools, but some plants and trees have quite a tenacious sap that can be quite difficult to remove.
The sap from mulberries for example can be very sticky and hard to remove. Many plants and trees, such as figs, euphorbias, and Chinese star jasmines exude a milky white latex which can really gum up to pruning tools.
The Best Ways to Remove Tree Sap from Your Pruning Tools
When cleaning sap and built-up grime from pruning tools, don’t use scourers, sandpaper (brown aluminium oxide or black silicon carbide sandpapers for metals) or steel wool, as these scratch up the metal of the blades. These abrasives may be useful for restoration work when removing rust from badly neglected tools, but they’re not for everyday general cleaning!
A better way to remove resistant sap from pruning tools is by gently dissolving it using the following methods below:
Dishwashing Liquid
The first resort when removing stubborn sap and gum from pruning tools should always be the tried-and-true kitchen method for cleaning pots and pans, and that’s using dishwashing soap with water and a scrubbing brush.
If this works then there’s no need to use anything more exotic, expensive or messy!
Vegetable Oil
The milky sap from fig trees, which is generally hard to remove, and quite irritant if it gets on your skin, comes clean off effortlessly by wiping it with a paper towel, or piece of cloth, with a few drops of vegetable oil on it.
Any kind of vegetable oil can be used for this purpose, and usually works on most kinds of tree and plant sap.
The thinner grades of vegetable oil can also be used to wipe down pruning tool blades after cleaning to stop them rusting. The thicker, more viscous vegetable oils tend to thicken and gum up more easily. The reason we don’t use synthetic mineral oils to prevent rust on pruning tools is because they’re not food-safe and would get into the pruning cuts.
If any of these methods mentioned above don’t work, then we can try something a bit more effective, but messier.
Mineral Turpentine
Mineral turpentine, also known as mineral spirits or white spirit, is a petroleum-based solvent that’s used as a paint thinner for diluting oil-based paints and for cleaning brushes. It’s quite smelly, so it should be used outside, and it’s a good idea to wear gloves when using it.
A few drops of turpentine on a rag will quickly remove any sap or gum from pruning tools with a bit of a rub.
Here’s a small folding pruning saw that was used to prune mulberry branches. The sap has stuck quite hard on the blade and can’t be removed with either a soapy brush or vegetable oil.
A quick wipe with mineral turpentine on one side of the blade makes it brilliantly clean, but some sappy wood is still stuck in the teeth near the tip of the saw.
Cleaning Out Sap Between Saw Teeth
Using a cloth moistened with mineral turpentine works well on the flat blades of secateurs, loppers and shears, but it’s difficult to get between the teeth of a pruning saw to clean out any sappy sawdust stuck in there.
Any easy way to clean out in-between saw teeth is with a wire brush. Push the brush only in one direction, towards the points of the saw teeth. The wire bristles will push out any debris stuck between the saw teeth.
Penetrating Oil
Penetrating oils are very thin (low-viscosity) synthetic mineral oils that easily seep into narrow spaces to free rusted mechanical parts (such as nuts and bolts) that need to be separated.
They’re just as effective as mineral turpentine in dissolving sap and gum that’s stuck on pruning tools, with the advantage of being far less smelly.
This is the other side of the folding pruning saw blade, cleaned with a cloth sprayed with some WD-40, a popular brand of penetrating oil. Once again, the blade is spotlessly clean.
With this many options, there’s bound to be something readily available in the home to clean dirty pruning tools.
Why clean pruning tools? Clean pruning tools are less prone to rust, so they last much longer. They also cut much more cleanly and with less effort than gummed up, neglected tools which have stuff stuck to their blades that makes it harder for the blade to glide through the cut due to increased friction.