Adhesive

There are many glues and adhesives that are used in kayaking.

• One-part adhesives are ready-to-use.
• Two-part adhesives have to be mixed to be used. Some require a catalyst in small volumes - ratios of resin to catalyst may be 100 to 1 or greater. Others are non-catalytic and are mixed in lower ratios like 1:1, 2:1, 5:1 or similar. Two-part adhesives tend to have longer shelf lives than one-part, since one-part are ready to cure. Two-part adhesives also tend to create the strongest bonds, are more expensive and are harder to find in retail outlets.

If the adhesives you are using are not strong enough, look up structural adhesives. These are formulations that go well beyond the capacity of the kind of adhesives you'll find available for consumers. They are only sold to industrial customers, but some online vendors will sell them. Some are listed below.

Common adhesives include:

• One-part Adhesives
  • Aquaseal is an amazingly strong glue and sealant for fabrics (including neoprene) and other stuff. When used on neoprene, the neoprene will tear before the Aquaseal lets go.
  • Contact Cement is useful for gluing in minicel and other foams. It can also be used to glue pads for D-rings or other fittings to the inside of a hull. The water-based "green" version of contact cement have been disappointing in wet usage - stick to the stinky versions and be careful with the fumes.
  • Cyanoacrylates are better known as super glue or crazy glue. These are very strong glues that only hold with tightly fitted surfaces. This tends to be a relatively brittle glue. There are industrial formulations of CA glues that are toughened (e.g. Loctite 411) - if these are still not tough enough, consider a urethane adhesive.
  • Goop comes in various variants and Marine Goop is probably one you should know about. It's a general purpose glue for sticking most stuff to most other stuff.
  • Hot glue is a solid stick of glue melted in a glue gun and applied to a surface. Used by some for gluing parts temporarily or for parts that need frequent replacing. There are many types of hot glue. Most of the stuff in retail is thermoplastic - it can be remelted and removed or allow repositioning of a part. There are also industrial thermosets that, once melted, cannot be remelted and are basically permanent.
  • Neoprene cement is specifically for neoprene. You can skip sewing neoprene with this stuff.
  • One-part Urethane - there are many variations of this. Aquaseal, 3M5200, Polyurethane wood glues and others are all one-part urethanes. Not as strong as two-part urethanes but these can be very strong. Since there are so many variations, choose the one with the properties closest to what you need.
  • Polyurethane wood glues (Probond, Gorilla Glue etc) are good for tight joints in wood and are fairly water resistant. This is not a good gap-filling glue and is weak if used to fill a large space. When used to fill a joint, the glue will expand and create a weak foam. If you can't get a tight joint, use epoxy.
  • PSA stands for "pressure sensitive adhesive" and is a term you'll occasionally see. PSA is also referred to as "peel and stick", since the glue is covered with a waxed paper covering that is peeled off to expose the glue. Many outfitting products are sold with PSA - minicel hip, thigh and seat pads among other things.
  • PVA glues are good for wood, but disappointing for wet environments. The latest waterproof versions are worth a look.
  • Sikaflex makes several sealants and adhesives that are good for installing bulkheads or even gluing bits onto a fiberglass hull.
  • Silicone bathtub sealant can be used as a glue for things that you may want to remove. Don't rely on it 100%, as it can let go under high loads.
  • Solvents are used for some plastics. They dissolve the plastic parts and when the solvent evaporates, the plastic hardens and bonds together. Polystyrene, PVC and other plastics can use solvents. Useless for gluing the plastic to another material. If you have the option of using something other than a solvent, consider it, as solvents tend to reduce the strength of the plastic - for example, polycarbonate loses toughness when adhered with solvents.
  • Special adhesives for low-surface-energy plastics like polyethylene, polypropylene and similar are sold by Loctite, 3M and others. These glues are quite expensive.
  • Special formulations of contact cement for minicel and plastic-to-plastic gluing ares sold in many paddling shops. This is quite good for gluing to Royalex hulls.
  • 3M 5200 is a very tough adhesive and sealant. This stuff will stick to almost anything (but not polypropylene or polyethylene) and is very difficult to remove. Do not use this on anything unless you intend it to be permanent. Normal 5200 takes up to 7 days to cure. There is a fast-cure version available.
  • 3M 4200 is also tough and tenacious, though less so that 5200. Also available in regular and fast-cure versions.
  • Vinyl Cement is used to glue PVC materials such as heavy dry bags.
  • White glue is usually the white form of PVA - see above.
  • Yellow glue is usually carpenter's glue - a variant of PVA - see above.
• Two-Part Adhesives
  • Epoxy is multi-purpose and is one of the strongest adhesives. If it breaks on impact, consider a two-part urethane. The latter may be more flexible than epoxy, but can stand quite high impact.
  • Polyester and vinylester resins can be used as adhesives, but epoxy, while more expensive, is better for about the same amount of trouble.
  • Two-part acrylic adhesive These structural adhesives are good for a number of plastics and, in particular, polycarbonates such as those used in Carbonlite 2000 kayaks (see Hull repair).
  • Two-part Urethane These are some of the toughest adhesives around. If epoxy is too brittle, this is the stuff to buy. Expensive and not sold to consumers - you'll have to find an industrial supplier to buy from.