GLUES & SEALANTS

Ranger Hope © 2008

There are six main glue types commonly used in boats:

 Animal Glues & Resins:

 Non waterproof and unsuitable for exterior use.

PVA (Polyvinyl Acetate):

Non waterproof and unsuitable for exterior use.

Rubber:

Contact adhesives that may be natural or synthetic. They are applied to both surfaces and allowed to partially dry before bonding together.

Melamine-Urea:

Cascamite (Casco urea formaldehyde) is a powder that is mixed with water with only a few hours shelf life. It is water resistant but brittle with poor filling qualities..

Aerolite is a two part catalyst and resin powder with water mix. The powder & water mix has a shelf life of a few days.The clear catalyst is applied to one surface and creamy resin applied to the other, allowing the coating of all surfaces prior to the event of bonding. Useful in tricky clamping up operations such as laminating multiple timbers or stich and glue construction where time is a consideration.

Epoxies:

Two part with a hardener and a resin and a shelf life of an hour or two, epoxy resin glues are now universally used in marine timber construction. They are waterproof, very strong but do not penetrate the end grain of timber. The West System successfully uses additives and extenders to modify the qualities of epoxy resins for composite construction.

Resorcinols:

Aerodux or Cascophen are superior two parts with good spreading qualities. They are fully waterproof and UV resistant with a few days shelf life after mixing. They are not gap filling.

Rubber=1    Melamine Urea=2    Epoxy Resins=3     Resorcinols=4

APPLICATIONS FOR TYPES OF GLUES
 

Metal

Fabric

Rubber

Wood

Paper

Ceramic

Metal

2   3

1

1  2  3

1  3

1

2  3

Fabric

1

1

1

1

1

1

Rubber

1  2  3

1

1  2  3

1  2

1

1

Wood

1  3

1

1  2

2  3  4

1

1  3

Paper

1

1

1

1

1

1  2  3

Ceramic

2  3

1

1  2

1  2

1

2

Thermoplastic

1  2  3

1

1

1

1

1

Modern bedding sealants are increasingly being used as adhesives with success.

Sealants

Sealants are used to form tough but flexible gaskets between fittings for insulation, waterproofing and increasingly as a bedding adhesive.

Traditional sealants:

Shellac:

Shellac, a natural resin, is nowadays more commonly associated with French polish for furniture finishing. It is dissolved in methylated spirit and was used as a bedding material under decking as it does not dissolved in water or by the action of the oils in wood.

Tar:

Stockholm tar with its distinctive smell is still used to waterproof natural fibre ropes, yarn and canvas.

Pitch:

A solid form of tar at normal temperatures, it is melted and laid into the gaps between deck planking to seal them.  Geofferies Marine Glue

Putty:

A linseed oil and chalk mixture that was fortified with powdered white lead (lead oxide) but is now commonly mixed with the less toxic red metal primer paint, and used to seal the plank seams in timber carvel construction.

Mastic:

Very slow drying natural or mineral oil pastes that provides a sticky waterproof seal that is flexible. As mastics age they dry, shrink and crack away from the surfaces. They are most successfully used as gaskets rather than surface fillets or beadings.

  

Modern sealants:

Polyurethane:

Form a permanent bond and should not be used for fittings that require to be moved. Not suitable for ABS type plastics. Some are not suitable for overpainting. Liquid nails, Construction adhesive

Polysulphide:

Single and two part varieties provide a rubber like flexible sealant. They can be premoulded to form gaskets and components can be disassembled with varying degrees of ease. They must be applied to dry surfaces and oily timber will require sealing with a primer. Most can be sanded and overpainted. Sikaflex.

Silicone:

Bond well to all surfaces to form a highly elastic seal. Most can be disassembled with ease and are not paintable. They are readily available and you will get a quality of Sealant that matches the price you are willing to pay for.

Exellent=1     Very good=2     Good=3     Not Recommended=4

Sealant/Bedding table    

Material

Polysulphide

Polyurethane

Silicone
ABS to GRP

4

4

3

ABS to Wood

4

4

3

Deck/hull joints

1

1

2

Deck seams

1

4

4

Electrical insulation

2

1

1

GRP to GRP

2

1

2

GRP to glass

2

1

2

Glass to metal

2

1

2

Glass to vinyl

4

4

3

Glass to wood

1

2

3

Metal to wood

1

2

3

GRP to metal

1

1

2

Plank seams underwater

1

4

4

GRP to plastic

4

4

2

Plastic to wood

4

4

3

GRP to wood

1

1

2