A colourful way to mark your bales

Doing a job you have done hundreds of times before, the mind can start to wander.

Last year while drifting along on the tractor, Mike Sherwood’s thoughts turned to marking bales.

Silage for the 100 beef sucklers and followers at Dudwell Farm, Burwash, goes into steel pallet-based round feeders.

The right bale must go in the right feeder, and while it’s easy to remember in summer which section of which stack is first cut grass, second cut, new ley, permanent pasture and so on, by mid-winter it is harder.

And harder still for bales carried over from the previous season.

Like others, Mr Sherwood used to mark batches manually with road paint.

But he wanted to do the job from the tractor seat, using a simple, easy-to-record code that would stay clearly visible for a couple of years.

So he set to ponder which material to use and how to apply it.

Move over, Da Vinci

Livestock marking aerosols solved the paint question.

Relatively cheap and available from any farming outlet, the solvent is wrap-friendly and the bright, persistent colours stick even to damp surfaces.

The challenge was to operate the cans remotely.

Mike Sherwood’s solution – a triple-colour, electrically powered delivery system bolted to the farm’s bale grab – is neat, effective and well made.

The foundation is a sturdy plate frame with holders for three cans, protected by an aluminium cover.

Each can wears a small aluminium hat, into which screws an extended nozzle.

Nozzles poke through the baseplate like machine guns in a tank turret, firing paint on to the target bale while this is held in the grab.

The smart bit is the way the aerosols are operated.

A shaft above the cans carries individual rocker arms, much like an engine’s.

One side of the rocker hovers over the can’s hat, the other contacts a 12V solenoid.

On pushing one of the cab control box buttons the solenoid flicks up, pushing the rocker down on the spray can’s cap exactly as you would thumb it.

The solenoid operates for as long as the cab button is pushed, delivering the required spray burst.

An adjuster on each rocker tip makes sure the can cap travels full-stroke, while a spring keeps each solenoid core in place during aerosol changes.


From talking over the design with a paint specialist, Mike Sherwood knew he would face problems with nozzle clogging and poor can agitation.

So he headed them off from the start.

Clogging stems from the tackiness of the paint and can’t easily be beaten.

But nozzles block mostly when not used for a while, like over mealtimes or overnight.

The answer is a quick dunk in white spirit – which is why they unscrew, and why Mr Sherwood carries a cleaning kit on the tractor.

Shaking the aerosols is tackled in a very enterprising way.

Three spare cans rattle round on a spindle under power from a 12V car wiper motors, keeping the contents thoroughly mixed.

When paint delivery from one of the cans in service starts to fade, the sets are swapped over.


Bales are marked with up to three colours.

A record sheet for each stack records the code, the stack row, the number of bales with the code and what is in them.

Red, yellow and orange colours show best on black wrap, giving 15 combinations if used singly as well as together.

If that is not enough, coding can be extended with dark colours on light wrap.

Paint smearing is only a problem if the bale is not placed heel-down while stacking, reports Mr Sherwood.

Even then the smear doesn’t affect visibility, he adds.

Running costs of the device are very low, he says.

Aerosols are about 4 each and will mark at least 100 bales, and it’s not necessary to code every one.

It is usually enough to mark changeover bales in the stack and record the number in that batch.

Downtime is short.

Swapping a full set of cans or nozzles takes about one minute, while nozzle cleaning needs much the same.

And build cost?

Mr Sherwood set himself a 150 limit on materials.

Solenoids cost 12 each from RS Components, control box switches come from Claas at 17.

Other bits were sourced and machined on the farm, so the unit came in well under budget.