Wonkee Donkee advises that you to clean your tools as soon as you have finished using them; it is much quicker and easier this way.
The best way to clean your tools is to simply rinse, however a mild detergent may be required to remove more stubborn debris.
It is much easier to remove any residue (remaining plaster or render for example) whilst it is still wet.
However, dried on plaster can be removed using an everyday household scourer or scrubbing brush. If the debris is more stubborn, wire wool or a chisel can be used instead.
Wonkee Donkee TOP TIP
Use an old toothbrush to get in-between the prongs and tines of the scratcher.