Epoxy Resin

What is epoxy resin?

Epoxy resin (INCI: Bisphenol A Epoxy Resin; chemically DGEBA — diglycidyl ether of bisphenol A) is a thermosetting polymer made by reacting bisphenol A with epichlorohydrin. In its liquid, uncured form it's one half of a two-part system — mixed with a hardener to set into a rigid, strong bond. It's everywhere in modern materials:

• Adhesives — "5-minute epoxy", structural glues.
• Craft / casting resin — jewellery, art, decorative pours.
• Coatings — epoxy floors, protective and marine coatings.
• Electronics — circuit-board laminates, component potting.

The single most important fact for allergy is the cured-versus-uncured distinction: only liquid, uncured epoxy sensitises. Fully cured epoxy is chemically inert, so a finished epoxy object doesn't cause the allergy — the risk is entirely in handling the wet resin during mixing and application.

Why epoxy causes reactions

The DGEBA molecule carries two highly reactive epoxide groups that bind skin-protein residues (lysine, cysteine, histidine) to form stable haptens — making it an efficient sensitiser, even after fairly brief contact with the liquid. Clinically it stands out for:

• Occupational weight. Epoxy allergy is among the most common causes of occupational contact dermatitis — construction, flooring, electronics, aerospace, marine trades.
• The craft-resin wave. Home casting resin put a serious workplace allergen into living rooms, driving consumer sensitisation.
• Airborne reactions. Dust from sanding or cutting can cause face and eyelid dermatitis, and there's a respiratory-sensitisation risk too.
• Persistence. Once established it's often severe and long-lasting, with some cross-reactivity to other epoxy systems.

Where it's found

• Two-part epoxy adhesives — hardware-store glues.
• Craft/casting resin kits — jewellery and art.
• Epoxy floor and protective coatings.
• Electronics manufacturing — laminates and potting compounds.

How to identify exposure

• History of skin contact with liquid two-part resin systems.
• Hand/forearm dermatitis tracking resin use (or facial dermatitis from dust/fumes).
• Patch testing with DGEBA (the standard epoxy test preparation).

Safer handling & alternatives

• Avoid skin contact with the wet resin and hardener; ventilate well.
• Epoxy-rated gloves (latex is permeable; change nitrile often), eye protection, dust control when sanding.
• Pre-cured / no-mix products eliminate uncured-monomer exposure.
• Different adhesive chemistry (e.g. cyanoacrylate) for some jobs — though each has its own profile.
• For confirmed allergy, strict avoidance of uncured epoxy and an occupational-dermatology review for workplace adjustments.

The bottom line

Epoxy resin is a workhorse two-part adhesive and craft material — and a potent, often persistent contact allergen, but only in its uncured liquid form. Finished, fully cured epoxy is inert. So the rule is simple: respect the wet stage. Keep liquid resin off your skin, ventilate, control the dust, and if you''re sensitised, avoid uncured epoxy and confirm it with DGEBA patch testing.