Bonding Theory and Techniques for Shoe Resoling

Nov 5

2 min read

Updated: 1 day ago

Bonding is the predominant assembly method in shoe repair and resoling. Understanding the techniques is essential for reliable, lasting repairs.

A craftsperson working on a shoe sole during a repair.

Identifying materials

A shoe repair begins with a careful examination of the footwear and identification of its materials, whether solid or expanded. Common materials include:

EVA (microporous) — used mainly for cushioning in running shoe midsoles.
PVC — used primarily in acid-resistant safety shoe soles and now also common in fashion.
Nylon — used for inserts with varying degrees of elasticity, especially in sports footwear.
Para — derived from vulcanised natural latex and used for certain soles.
Leather, hide, Thunit (an economical vegan alternative to leather), TR and rubber.

Shoe resoling: preparing the surfaces

The surfaces to be bonded must be clean, dry and free from grease and dust.

Clean and degrease both surfaces if necessary.
Leather and rubber often require roughing: it removes contaminants and increases the bonding area.
Smooth, difficult surfaces may need fine sanding; remove all residue afterwards.
Where grease or plasticisers are present, clean with Überkoll Solvente Cleaner before bonding.

Applying primers

Primer prepares the surface before bonding. The range includes:

Überkoll Alogenante — improves adhesion to difficult substrates; required before Überkoll Poliuretano on vulcanised rubber and TR/SBR materials.
Überkoll Ancorante (PU/PVC) — improves adhesion on difficult substrates with polyurethane and polychloroprene adhesives.
Überkoll Primer EVA — improves adhesion to expanded EVA/SBR materials.

Tradigo tip

To speed primer drying and improve performance, adding 4–5% Überkoll Attivatore may be useful.

Applying the adhesive

The adhesive and substrates should be at room temperature. Avoid cold adhesive or cold, damp surfaces to prevent condensation bubbles. Überkoll Attivatore may be used at the specified proportions to accelerate crosslinking.

Überkoll Poliuretano requires heat reactivation with a hot-air gun or infrared oven. Non-polyurethane adhesives generally do not, except for Überkoll T70 Superchiaro mixed with Attivatore, used for example in climbing shoes.

Apply first to the less porous surface, then to the more porous one. Highly absorbent materials may benefit from a second coat once the first is dry. Avoid draughts while the adhesive is wet.

Assembly and finishing

If possible, press mechanically with a pneumatic cushion; alternatively, use a roller or rubber mallet. Avoid air bubbles and position the parts carefully, as they are difficult to reposition once bonded.

Allow the adhesive to cure fully before trimming, finishing and cleaning the shoe.