epoxy | solvents | sanding dust | general
Working with epoxy
Epoxy comes with certain health hazards that have to be adressed. Chemicals in some epoxy resin systems have additional health effects. Finished, hardened epoxy products are practically non-toxic unless they are cut, sanded, or burned.
The resin is considered relatively harmless, but the curing agent (hardener) is corrosive and toxic. The most common problem comes from repeated skin contact with non-hardened epoxy. The worst case is a developed skin allergy, which effectively puts an end to the strip boatbuilding career (or rather; a future with SOF-kayaks). This condition can sneak up on you since it is apparently cumulative. Worst are the older types of hardeners, based on aliphatic polyamines. Modern hardeners often contain amine adducts or polyamides that are less aggressive. But the rule is: never non hardened epoxy in contact with the skin.
The evaporation is extremely slow with solvent free epoxy and the vapors are heavier than air, so the risk of hazardous levels of vapors in the air is small in a normally ventilated shop (epoxy glue or paint is often mixed with solvent and needs much more strict safety precautions).
Sanding half cured epoxy (= is epoxy cured less than a week) may lead to throat irritation and allergic symptoms - always use a dust mask when sanding.
Be extra careful if you have an allergy, asthma, hay fever, are tired, have a cold or a virus infection.
- Avoid epoxy on the skin. Use gloves and cover bare skin. Non hardened epoxy can be washed off with warm water and soap. Wash immediately! If you wait you will have to scrub with the risk of damaging the skin. Never ever use solvents on the skin! They remove the natural protection.
- Remove rings, watch etc when working with epoxy.
- Don´t smoke or eat while working.
- Epoxy on the clothes - change them and wash the skin.
- Make sure the ventilation is good.
- Epoxy in the eyes? - rinse well for 15 minutes and go see a physician (bring the product information)
- Skin irritations? - give the project a rest for a week or two and be more careful when continuing.
Some building manuals talk about penetrating epoxies for a first coat, or thinning the epoxy to improve saturation. My experience is that this is a bad idea.
- Excessive penetration is not beneficial. Saturating the wood increases weight and reduces the flexibility of the wood.
- Solvents makes the epoxy far more hazardous to use
- Solvent slows down the curing, in some cases may even prevent a proper curing.
- Thinned epoxy is less efficient for wetting out fibre glass and may increase the risk of delamination
To increase the penetration more than the normal tenth of a millimeter, should this in a special situation be an advantage, I recommend heating the epoxy and the wood (approx 30 degrees C), apply the epoxy and then let the temperature slowly go down. Contracting air in the wood will pull the thin epoxy in.
All solvents are potentially dangerous; toxic, hazardous to inhale, irritating to the skin and they represent a fire hazard.
- Always use the least dangerous solvent in a given situation (e.g. clean tools in white vinegar instead of expensive supersolvents with unpronounceable names).
- Avoid solvents when possible. Use disposable brushes for all except perhaps the last finishing - cleaning brushes from epoxy is expensive, stupid, unhealthy and inefficient.
- Avoid skin contact.
- Don´t smoke close to solvents. Avoid open fire.
- Good ventilation is a must, best outdoors.
- Do not use potentially dangerous tools - e.g. the table saw - directly after using with solvents
Machine sanding of wood produces considerable amounts of dust - some of the species contains agents that are allergy prone (cedar, mahogany, teak, ebenholz, iroko et al). Most pine and fir varieties are relatively harmless in this respect. High concentrations of dust and solvents may selfcombust and should be avoided.
- Make sure all electric cables and plugs are in good shape and properly grounded. A residual current device (RCD) may save lives.
- Follow the safety advices for electrical machines even if the sometimes may be counterproductive to some of the more creative uses a builder might fancy trying. Accidents happens surprisingly quick and may have consequences for a very long time. The first-aid box is a poor substitute for keeping the fingers away from the table saw blade.
- A boat builders shop comes with a certain fire hazard, with sanding dust, oils, paints and solvents. No place for carelessness.