Trade Secrets: Epoxy waste with expert David Johnson
In the days of each and everyone of us adapting our lives to be more environmentally friendly when working with epoxy, there is always a way to minimise your leftovers. David Johnson uses his many years of epoxy experience to offer insights into ways he has become savvy with epoxy waste.
Working on Little Wing, a Sandhopper 19″ keel boat, David explains, I had just applied the final West System Epoxy finishing coats on a new modified wood/composite rudder I had made for Little Wing, and looked at the straining bag of waste, after I had swept away all the mess.
The rudder blank started life as laminations of Spruce, Mahogany and Western Red Cedar, glued with epoxy, shaped and sheathed in 300g/m.sq glass cloth.
I built a new rudder to replace one I had made in a similar fashion 10 years previously, but with a thinner foil section. Examining the old rudder after all that time racing, and being left on the boat, there was hardly a mark on it, with no signs of moisture entering the timber core. A great testament to wood/composite construction and its lifespan.
I used a planer thicknesser and a circular sawbench to cut planks for the laminations from bulk board I had purchased, the sawblade lost 3mm of wood per cut, the thicknessing, a large pile of shavings, and the final aerofoil shaping of the blank a total of 1.3kg of wood taken off a 4.2kg blank.
I was really very pleased with the result, cedar is lovely to work with, and hand planing a foil section with a sharp blade produces satisfying curling ribbons of transparent timber, that smell like the inside of a guitar.
I suppose I can burn the waste timber and shavings in the winter, but I looked closely at the other waste, pots, mixing sticks, roller trays, rollers, brushes, plastic squeegees and of course gloves.
I remembered my days in production Glass Fibre boat building, and recalled how we used to weigh the scrap bin at the end of the week, containing cured waste polyester resin, dry glass fibre, and cured laminate flashing from the trimming process. We weighed the scrap simply because, within it was raw material wastage, and importantly the labour content to manufacture it. At that time little thought was taken that all this scrap would end in landfill.
I consider myself frugal when working with epoxy, with experience I have come to know just how much mixed resin/hardener/filler I need to undertake the work I have planned, it’s amazing how much work a squirt of resin and a squirt of hardener will do.
I’m something of an expert at work planning too, so I have several epoxy jobs on the go at the same time, and also perhaps a chair that needs fixing if I have some waste. Strangely whilst building this rudder I was repairing a carbon fibre bicycle frame!!!! That is definitely multi tasking.
So with good work planning and estimating, it’s possible to be more efficient and not throw unrecyclable waste epoxy in the rubbish bin. Work planning is essential from another aspect, as if mixed sufficiently and at the correct ratio epoxy will cure, and will wait for no man or woman, so there is an inbuilt motivating force within the cure time, you should see a team conducting an osmosis coating of 6 coats in a day, they are highly motivated!!!!
What about the other , so called ‘consumable’ products that we have at our disposal?
Good quality pots of the same size will always define your working times, and can be used many times, if you break the cured waste out carefully by rolling the sides of the pot before pushing on the bottom, and are recyclable once they have broken. I have seen people all over the world using everything from yoghurt pots to sawn in half milk bottles, to baked bean tins to washing up bowls. I say if you want a good job, use the best tools, these consumables are part of your epoxy toolkit. It’s possible to throw your yoghurt pots in the recycling bag, but not when they are full of cured unremovable epoxy.
I once saw a production boat builder cutting mixing sticks from scrap ply at probably £ 40/hr, that was tragedy. Good hardwood stirrers and tongue depressor type mixing sticks cost barely anything, make mixing much easier, as you can get right into the corner of the pot…….remember that residue. I make a tongue depressor last for the day by simply using my gloves to wipe it as I dispose of them. A hardwood stirrer I will make last for a few jobs by cleaning it. We have now made a recycled plastic mixing stick/clean up tool that makes filleting and cleaning so much easier and will is reusable.
Epoxy is not expensive, but its not that cheap either, good tools make for good work and a little thought for work planning is hugely beneficial.
Find out more about safe epoxy disposal.