Health and Safety: ResinsDateline: 08/25/98
Composite materials pose health hazards, both in their uncured and in their cured forms. These hazards, though, shouldn't scare you away from the materials: with proper precautions, the risks can be minimized and even eliminated.
In this series, I will give a brief overview of the health and safety issues involved in working with composites. Please remember that this is only an introduction: before using any material or process, you should fully investigate the potential hazards.
The first article in the series covers resins and related materials.
Polymers used as matrices, and those used as adhesives, probably pose the highest hazard when working with composites. Most resins do not pose a respiratory hazard, but some curing agents and many solvents used in conjuction with resins do. Thermoplastics are pretty much inert and pose little or no risk (except for burns when they are melted).
The primary hazard with resins is direct contact. Of course, eye contact with any foreign substance should always be avoided, but it is also important to avoid skin contact with resins, curing agents, and solvents. Problems range from staining and irritation to organ damage, and many substances are suspected or known carcinogens.
Most resins are skin sensitizers, meaning that symptoms can develop or become worse after repeated or prolonged contact. I have actually seen a few people who have become so sensitized that they cannot be in the same room as uncured resins.
Some contact hazards may not be obvious at first. A few years ago I was holding a small piece of wood in place while someone else applied a cyanocrylate (superglue) to it. Some of the adhesive got on one of my fingers, and when the technician sprayed an accelerator, the adhesive immediately exothermed. Not only did I have a tough time getting the cured adhesive off of my finger, but I also got a small burn in the process.
Protective clothing, including goggles and gloves, should always be worn when mixing and handling resins. Prepregs are partially crosslinked, so the risk is lower, but gloves should still be worn. Not only can you develop sensitivity to prepreg resins, but oils from your hand can contaminate the composite.
If you do get a resin or adhesive on your skin, wash immediately with soap and water or a waterless cleaner such as those with a citrus base (some materials are water soluble, others are not). Do not use a solvent such as acetone or alcohol. Not only can this be a hazard in itself, but the solvents will remove skin oils which act as a protective barrier.
When selecting gloves, make sure they protect against the materials you are handling. Many gloves dissolve in solvents. Most safety catalogs list the materials gloves are resistant to. If you're not sure, fill a glove finger with the material in question and wait a while to see if the glove holds up.
Prepregs can be difficult to handle with gloves, but don't give in to the urge to work bare-handed. My personal favorite glove for working with prepregs is the Layup Glove from Comasec Safety, which I reviewed in my Tools of the Trade Column.
Although the focus of this discussion has been on contact hazards, adequate ventilation should also be provided to minimize respiratory risks. In extreme cases, respirators may be required, but it is always best to keep the substance out of the work area in the first place.
The OSHA Technical Manual section on Advanced Composites covers the hazards of various resins, curing agents, and solvents in detail. It includes a table organs targeted and health effects of several materials.
Of course, you should always read the MSDS, or Material Safety Data Sheet, for any material. These show the hazards (including routes of entry), first aid measures, accident measures, and protective options.
Many manufacturers and distributors place MSDS's on their Web sites, and there are a few sites with collections. Two of the better collections are at:Previous Features