Why composite dust deserves your full attention

Anyone who has trimmed a carbon fibre panel or sanded back a cured laminate knows the telltale grey film that settles on every surface in the workshop. That film is a warning sign. Composites bring together two very different hazards: brittle reinforcing fibres — carbon, glass, aramid — and a resin matrix that is often epoxy. When you cut, grind or sand, you create a mixture of fine particulates and partially cured resin dust, and the smallest fraction can travel deep into your airways.

Respirable dust is the fraction that matters most. It is too small to see individually, it hangs in the air far longer than the visible flakes, and it can reach the gas-exchange regions of the lungs. Glass and carbon fibres can irritate the throat, nose and eyes, and repeated exposure is linked with coughing, wheezing and, in some people, the development of occupational asthma. Epoxy dust is a known skin and respiratory sensitiser, which means once you are sensitised, even tiny future exposures can trigger a reaction.

There is a practical wrinkle too: carbon fibre dust is electrically conductive. Allowed to build up inside power tools, control boxes or test rigs, it can cause short circuits. Treat it as both a health hazard and an equipment hazard.

Cut wet whenever the geometry allows

The single most effective control is also the cheapest. Water traps dust at the point of generation, so it never becomes airborne in the first place.

• Use a water-fed diamond saw or a wet-cutting blade for straight trims on flat panels, with a steady trickle rather than a flood.
• Wet-sand by hand with wet-and-dry paper and a spray bottle, keeping the surface visibly damp rather than soaked.
• For small cuts, a light mist from a hand sprayer over the cut line reduces the plume dramatically.
• Keep a shallow tray of water under the work where practical, so debris falls into liquid instead of onto the bench.

Two cautions. First, water and electricity do not mix, so use an RCD-protected supply and keep cables, plugs and tool vents clear of the wet zone. Second, the sludge that results must never be allowed to dry out and re-release dust. Wipe it into a sealed bag while still wet, and label it as hazardous waste for your disposal route.

Capture dust at source with local extraction

When wet cutting is impractical — complex geometry, bonded assemblies, or work already installed — extract at the tool. An extraction shroud fitted to a die grinder or sander, connected to a suitable vacuum, captures the majority of dust before it reaches your breathing zone.

For composite work, a domestic vacuum is not acceptable, even with a bag. Use an M-class dust extractor as a minimum, and step up to H-class where the risk assessment calls for it. Check the filters are rated for fine particulate, keep hoses as short and smooth as possible, and empty or replace collection bags before they are more than about two-thirds full. Restricted airflow is the most common reason extraction quietly stops working.

Where you do a lot of flat sanding, a downdraught bench pulls dust away from your face. Fixed extraction systems are subject to thorough examination and testing at least every 14 months under UK COSHH requirements, so keep the records and act on any defects. A quick daily check — airflow indicator, visible dust, damaged hood — takes seconds and catches most faults.

Choose the right mask, then wear it properly

Respiratory protective equipment is your last line of defence, not your first, but it still has to be right.

• For dry trimming and sanding, an FFP3 disposable or a reusable half mask with P3 filters is the sensible baseline. FFP2 is generally not enough for fine composite dust.
• Tight-fitting masks must be face-fit tested for the individual wearer, and re-tested if your face shape changes — a beard, significant weight change or new eyewear all matter.
• The seal area must be clean shaven. Stubble lifts the mask edge and lets dust straight past.
• Perform a user seal check every time you put it on, and store the mask clean and dry — never slung on a dusty bench.
• If you wear a mask for hours at a time, or the work is hot and heavy, a powered respirator with a belt-pack unit is far more comfortable and usually gives better protection.

Don't overlook skin and eyes

Epoxy sensitisation is a career-limiting condition, and it often starts with dust settling on forearms and wrists. Wear nitrile gloves — not latex — and change them when they are contaminated. Long sleeves, disposable coveralls and wrap-around eye protection keep dust off skin and out of eyes. Wash hands and forearms before eating, drinking or using the toilet, and avoid carrying contaminated clothing home. A dedicated set of workwear that stays in the workshop is a simple, effective habit.

Housekeeping makes the difference

How you clean up determines how much dust you and your colleagues breathe tomorrow.

• Never dry sweep or use compressed air. Both put settled dust straight back into the air.
• Wipe surfaces with damp cloths, or use a wet vacuum with a suitable filter.
• Bag waste while wet where possible, seal it, and store it away from general rubbish.
• Keep composite work in a defined bay with good general ventilation, and keep dust-generating tasks away from electrical panels and precision equipment.
• Plan the job before you start: decide where the dust will go, then set up extraction, water and PPE to match.

None of this is complicated, and none of it needs expensive kit to begin with. Wet the cut, capture what you can, protect your airways and skin, and clean up wet. Do those four things consistently and you will keep your workshop healthier, your tools happier and your career longer.