FAQ's Copper Tools

Q: I thought copper was a soft metal. Does it stand up to garden use?

A: In its pure form, copper would be too soft a metal for garden tools. However, our tools are made from a range of copper alloys. The blades of all the tools are solid bronze containing over 90% copper - the remaining part is tin. Bronze is hardwearing and keeps a sharp edge better than pure copper. The collars of Sirius, Tuza and Hydra also have brass parts, an alloy of copper and zinc.

Q: How do you sharpen the tools?

A: There are two ways. Either file the blade with a fine metal file, or put it on a block of wood and peen (hammer) it. Peening is a skilled job but it's fun to learn!

Q: Won't copper go green over time?

A: No. The green in verdigris, which is formed when copper comes into contact with acid. Copper roofs have green verdigris because rainwater with its absorbed carbon dioxide is naturally slightly acidic. Groundwater is not naturally acidic. Even acidic soil is not acidic enough to cause verdigris. Our tools acquire a slight brown patina over time but it can be cleaned off easily with some polish if you want to restore the original shine.

Q: How long should they last?

A: These are long-lasting tools, which should outlast most of us. However, if for any reason you are unhappy with the tool we offer a no-quibble 10 year guarantee. We will refund or replace an unused tool. We will also repair or replace a faulty tool. Of course this excludes normal wear and tear. The handles and shafts are guaranteed for two years, and we supply replacements.

Q: Do the handles need any special care?

A: The small tool handles have been treated with a coat of linseed oil. The shafts and long handles are of untreated European hardwood. It is good practice to oil the handles from time to time, and store the tools out of rain and strong sunlight. You can also help the wood to seal by sanding it with very fine sandpaper, initially 150 grade and then even finer. Everyday use will also help to seal the wood and eventually they acquire a burnished shine. Do not wash the handles. Wipe with a damp cloth to clean.

Q: I have heard that slugs and snails receive an electric shock when they come into contact with copper.

A: I don't subscribe to the electric shock theory. I store my tools in an outside shed and one winter I noticed a snail's slime trail leading to the head of my copper spade. It went over the blade and onto the other side. Either that was an exceptional snail, or it didn't receive an electric shock. However, it is true that plants cultivated with copper tools are less attractive to slug and snails.

This is a short insight by Jane Cobbald into perhaps why gardeners find the influence of copper in the garden helpful. You can read further thoughts in her booklet "The story of copper garden tools."

“We live in the Earth’s magnetic field, which is sustained by the movement of the relatively high iron content in the Earth’s mantle. Any piece of iron can have its own magnetic field. The metal copper, on the other hand, is non-magnetic and highly electrically conductive.

We, and all other mammals, have iron in our blood. That is why our blood is red. It enables each of us to have our own independent magnetic field, anchored on our blood.

Slugs and snails do not have iron in their blood. Their blood contains haemocyanin, based on copper. This means that they do not have an independent magnetic field. As copper is conductive, they are highly sensitive to the Earth’s magnetic field. As they move along the ground, they are subject to the lines of magnetic force generated by the rotating core of the Earth.

Now, imagine that a diligent gardener has carefully transplanted their lettuce seedlings, using an iron tool. As the tool turned the soil, it left its magnetic signature. When night falls, the slugs and snails start on their slimy way, following the lines of force that they detect on the soil surface. When they reach this disturbance around the transplanted lettuces, they are forced to stop. They do not know where to go – the signal is not clear. They have to wait, and while they wait, they get hungry. And there go the lettuces. Using a copper tool leaves no magnetic disturbance, so there is nothing to attract the slimy molluscs.”

Q: Does copper deter earthworms?

A: Earthworms are annelids, a different family from slugs and snails (molluscs). Annelids have haemoglobin just like we and other mammals do, whereas molluscs such as slugs and snails have haemocyanin, based on copper. The use of copper tools should have no effect on the earthworm population.

Q: Doesn't copper poison the soil? I've been told hammering a copper nail into a tree can kill it.

A: Copper is a valuable trace element, which is in short supply, including in parts of New Zealand. It is contained in many fungicides and plant feeds. It its necessary for plant metabolism, particularly energy transfer. Our tools stay in the ground for a shorter time than a nail hammered into a tree. Regarding the nail in the tree, I've never met anyone who actually does this. However, too much of a good thing is bad for any living thing, including trees.

Q: Why did the human race move from the Bronze age to the Iron age? Is Iron better?

A: I suspect the reason was not to do with agriculture, but weapons of war. Iron and steel are harder than bronze, but more brittle. They cause more friction in the soil than bronze and do not keep their keen edges so well. Even more importantly, every piece of iron is magnetised to a greater of lesser extent. This may not be particularly relevant for weapons and armour but it is very significant when working with the soil