- Alex - Shogun Tools
FAQ – What should I do about rust/tarnish on my secateurs?
Clean any residual sap off your tools
Dry and lubricate after use
Attend to any minor surface oxidation with rust eraser or other methods outlined below
Now for the long story. Firstly, let’s get down a basic definition of oxidation, rust and tarnish/patina.
Oxidation put very simply is the reaction of different compounds in the presence of oxygen. Rust and tarnish are both forms of oxidation.
Rust is an ongoing corrosive oxidation of metals, usually in the presence of water (other compounds are sometimes involved such as salts which accelerate the process). It will continue to deteriorate the metal causing pitting, cracking and flaking. This is usually identifiable by its red-orange colouration. Rust is deterioration and if left to continue can cause significant damage to the metal.
Tarnish/Patina are commonly used interchangeably but technically patina refers to a form of oxidation that occurs on metal alloys containing bronze. Both result in the surface discolouration of metals, usually resulting in blue, green or black colouration. Patina is often desirable of antique or period items and modern custom knife makers often force patina on their knives using varying acidic substances for aesthetic and protective reasons. ‘Patina’ sounds a lot fancier and there are less negative connotations than ‘tarnish’, yet they are both self limiting forms of oxidation that don’t usually cause ongoing deterioration. In fact, they usually only affect the very surface of the metal and can actually prevent or limit the formation of rust.
So now we’re on the same page we can look at our tools and determine if we have a rust or tarnishing. The below image Photo 1 shows two pairs of carbon steel secateurs, the one on top shows tarnishing, and the one below has heavy rust (note the bubbling and pitting appearance of the metal).
If your tools are turning red/orange/brownish with an irregular surface you have a rust issue, if they are blue, green or black you likely have tarnishing. The best way to limit both is to keep your tools dry and well oiled (oil forms a barrier to oxygen therefore oxidation occurrence is limited). However, it is not practical to completely prevent oxygen contact to tools that are regularly used (unless you’re an astronaut) so it must be expected that one or more of these reactions will occur.
This is not so much an issue with the metal alloys used on our stainless steel secateurs but is still possible. Stainless steel, stains less but is not stain proof. If you have black marks on your stainless secateurs it is more likely to be sap build up rather than rust or tarnishing.
Carbon steel is more reactive and thus more prone to oxidation.
If you seccies look like the rusted ones in the bottom of the Photo 1, they will need a full re-grind and rebuild which is not covered in this article. But if you have only minor oxidation (ex. Photo 2) please follow the steps below.
In both cases of minor rusting or tarnishing the first step we recommend is cleaning your secateurs as sap from pruning will also show up as brown and black discolouration. We recommend and sell Razorsaw Sap Cleaner but you could also use a solvent such as ethanol. Apply to the surface (Photo 3), let sit for 30 seconds and wipe off with a paper towel or rag (Photo 4).
As we use our tools for work, we usually stop here with the cleaning and apply an oil such as our Camelia/Tsubaki oil to the entire surface of the tool as well as making sure to get some down inside the pivot point of the blades. You may also use something like Inox/WD40 or another commercially available lubricant. Open and close the seccies for 30 seconds to work the oil into the pivot point and apply a little more in front and behind the bolt to make sure it works it’s way in. Put them back in the pouch and you’re ready for work again!
If it’s been awhile since you cleaned your seccies and the sap build up is a bit more severe you can use a flexible/rubberised sanding block, fire steel wool or a kitchen scourer to remove more of the sap. Remember to oil everything when you’re finished.
If you’d prefer to return your seccies back to shiny bare metal there are a few ways to go about it. Remember the blackish oxide is protecting the metal so if parts of your secateurs were black when you bought them there is no need to polish these back to bare metal (you can if you want but we don’t recommend it).
For minor surface oxides we sell and recommend the Rust Eraser, this is like a pencil eraser embedded with fine abrasives. Use it like you would rubbing pencil off paper. Flush the moving joint well with lubricant (WD40/inox/etc) when done to remove any remaining grit and residue from the eraser and lubricate (Photo 5).
Or you could also use the sanding block, fine steel wool or kitchen scourer as above for the heavy sap removal.
To take it a step further you could also finish up with a metal polishing compound such as Autosol Metal Polish but this isn’t really necessary (Photo 6).