Evidence grade: A1 — TDS/spec-sheet data and university reference; B1 for trade practice Effort: Varies · minutes–hours · depends on the joint and the adhesive chosen
Decision: tight wood-to-wood joints get PVA wood glue (cheap, strong, forgiving); gappy, damaged, or mixed-material joints get epoxy (gap-filling, waterproof, demanding); small close-fitting quick fixes get superglue (fast, brittle, not structural). The joint decides, not the tube [1][2][3].
Know your three candidates
PVA / yellow wood glue — the default. Bonded properly, a PVA joint is stronger than the wood around it (one product's hard-maple shear data: 3,510 psi with 81% wood failure — the wood breaks before the glue does) [1]. It works on wood, particleboard, MDF, and plywood; cleans up with water; needs 15 minutes of open assembly time and solid clamping pressure to cure right [1]. It is not gap-filling — the joint must be snug — and it's an indoor, non-structural, non-load-bearing glue [1][2].
Epoxy — the gap-filler. A two-part system (resin + hardener) that bonds across gaps and sticks to materials PVA can't touch — metal, fiberglass, plastic (see Repair Lab B3 if you're tempted to try low-surface-energy plastics; standard epoxy won't bond PE/PP). It's waterproof, sands and shapes well, and handles heat better than PVA [2][3]. The price: exact mixing ratios, slow cure under clamp, and real safety discipline — skin sensitization is the main hazard [2].
Superglue (cyanoacrylate) — the specialist. Bonds in seconds and is excellent for small splits, cracks, and hard-to-clamp defect repair — but it is brittle, doesn't fill gaps, has a short shelf life, can't be reversed, and bonds skin instantly. It is not a general-purpose woodworking adhesive [2].
The decision table
| Joint | Use this |
|---|---|
| Clean, tight, well-fitting wood-to-wood (chairs, frames, boxes) | PVA wood glue — strongest bond for the money, water cleanup [1] |
| Worn, loose, or gappy joint (wobbly dowel, repaired tenon) | Epoxy — PVA needs a snug fit; epoxy fills and grips [2][3] |
| Wood to metal, fiberglass, or other mixed materials | Epoxy — PVA only glues porous cellulosic materials [1][2] |
| Anything that lives in water or outdoors (boat, garden) | Epoxy (waterproof) — PVA is not for exterior service [1][2] |
| Tiny split or hairline crack you can press closed, quick fix | Superglue — seconds, no clamp; don't ask it to hold a load [2] |
| Antique or heirloom furniture | Hide glue — reversible; epoxies and PVAs are forever [3] |
| Joint that will be stained afterward | PVA — cured epoxy blocks stain and stays visible; "if you plan to stain it after, you can't use epoxy" [3] |
Two rules that save every repair
- The surface must be clean and sound. "Epoxy won't stick well to old glue — remove old glue before applying epoxy" applies to all three adhesives: old glue, dust, and finish residue sabotage the bond [3]. On the physics of why, see Repair Lab B3.
- Clamping is part of the glue. PVA needs steady pressure to pull the joint closed and cure (30 minutes minimum open-to-clamped is typical) [1]; epoxy needs the joint held while it sets [3]. A joint glued without clamping is a hope, not a bond.
⚠️ Stop rules
- Structural or load-bearing applications — the PVA data sheet explicitly excludes structural/load-bearing use [1]; none of the three is a substitute for mechanical joinery or engineered hardware in safety-critical joints.
- Unknown substrates, contaminated wood, or oily exotic species — if you can't identify what you're bonding, test first or consult a professional.
- PPE/ventilation: PVA — minimal; avoid eye/skin contact per the label. Epoxy — nitrile gloves, eye protection, ventilation (skin sensitizer). Superglue — eye protection, ventilation, keep away from skin and cotton (instant bond). Read each product's label before mixing.
Honest limits
- "Stronger than the wood" data comes from lab shear tests on hard maple — real joints have gaps, contamination, and imperfect clamping, so field strength is lower.
- Epoxy's waterproofing assumes a proper cure at the right ratio — off-ratio mixes stay soft.
- Shelf life matters: old glue of any type can underperform; superglue's short life is the worst offender [2].
Sources
- Titebond Extend product data. https://www.mckillican.com/portal/public/Resource.ashx?id=272 — works on wood, particleboard, MDF, plywood; 15-minute open assembly time at 70°F/50% RH; hard-maple shear 3,510 psi with 81% wood failure; water cleanup; not for exterior or structural/load-bearing use.
- University of Michigan A&A Shop — adhesive overview. https://sites.google.com/umich.edu/aa-shop/resources/general-reference/glues — PVA is the default for clean tight wood joints, cheap and needs clamping; epoxy is gap-filling, mixed-material, waterproof, but toxic, needs careful mixing and PPE; superglue is for small splits/defects, brittle, no gap fill, short shelf life, non-reversible, bonds skin.
- Family Handyman — "Fast Furniture Fixes." https://www.familyhandyman.com/list/fast-furniture-fixes/ — epoxy won't stick well to old glue; remove old glue first; can't stain cured epoxy; epoxy bonds across gaps that other glues can't.
A metal-repair epoxy is sold for metal repair, not as a wood glue — pick the adhesive by the joint, not by what's on the shelf.
Repair Lab · Release 1 · Evidence last checked September 30, 2026 · A project of AOJEL