Phenol Formaldehyde Glue
Phenol Formaldehyde glue is the most commonly used glue in WATERPROOF contruction panels, beams and including many of the marine plywoods.
Here is a link to my page on Marine plywood standards and grades.
It is not easily available to home builders because it needs high pressure and temperature to cure.
What is Phenol Formaldehyde Glue
Phenol formaldehyde resins (PF) are a class of synthetic polymers produced by the reaction of phenol (an alcohol derived from benzine) with formaldehyde (derived from methane.)
Although the Phenol commonly used by manufacturers comes from petrochemical sources, it is possible to use Bio Oil from Pyrolysis sources to make the PF resin thus reducing dependence on fossil fuels. The link is to a research paper on the possibility of using bio oil. This is not used commercially at this time.
Bakelite, which is one of the first synthetic plastics that was widely manufactured, is a phenol formaldehyde resin. It was widely used as a moulding material and appeared in kitchen ware, clear coloured plastic objects such as hair bush handles, decorative boxes and countless other early plastic manufactured items. Early telephones were moulded from Bakelite.
Micarta, the plastic impregnated brown linen cloth board, is another early Phenol Formaldehyde product that has withstood the test of time.
PF is highly cross-linked and this makes the cured resin, hard, thermally stable and highly chemically resistant and waterproof.
Once the resin has set, it can no longer be reshaped except by mechanical methods such as drilling or machining.
Phenol Formaldehyde is also sometimes called phenolic resin.
Both Urea formaldehyde and Phenol formaldehyde products outgass formaldehyde after manufacture. Phenol formaldehyde does considerably less outgassing. For this reason it is sometimes recommended that construction grade plywood and wood panels which contain phenol formaldehyde, be substituted for furniture grade plywood which contains urea formaldehyde. Outgassing decreases substantially over time.
Here is an article that talks about outgassing of formaldehyde gas in wood products.
Any chemistry lover can read this article from Wikipedia.
What is Phenol Formaldehyde Used For?
Phenol Formaldehyde resins make superior wood adhesives and are widely used glues for construction grade wood panels such as plywood and oriented strand boards which need to be waterproof.
Part of the success of these adhesive resins is due to the formation of bonds between the glue and the phenol-like lignin which is a natural component of wood.
Phenol Resins are also used for moulding objects which can be insulating and heat-resistant. In that case various fillers are added such as fabric, fibres and flakes. Some uses are heat resistant appliance handles, distributor caps and brake linings. Snooker balls and circuit boards are other phenolic resin products.Britannica Encyclopedia article on Phenol-Formaldehyde Resin
The Chemical Company supplies phenolic resins to industry. It has an explanation of the 2 types of phenolic resins available: Novolacs and Resoles. Resoles are the resins used primarily for plywood and wood glues.
It's interesting to note that old fashioned blood glues owed their water resistance to their natural phenolic content.
Resorcinol based glue also owes its moisture resistance to naturally occuring phenols.
What are the Advantages of Phenol Formaldehyde glue?
- Type I moisture resistance is a stellar quality. This means that the glue resists to the boiling test where a sample is subjected to several cycles of boiling and drying. This superior water resistance makes the adhesive BS 1088, BS 6566 and AS/NZS 2272 compliant. Other factors come in play, such as the quality of the veneers, but the glue is acceptable for marine and exterior use.
- Sets hard and rigid.
- Phenol Formaldehyde has been around for long enough to have proved itself over the long term.
- Phenol Formaldehyde reacts with natural phenol-like lignin found in wood to improve glue to wood bond.
What are the Disadvantages of Phenol Formaldehyde (Phenolic resin) Glue
- It requires heat and pressure to cure.
- It is not readily available for amateur or small woodworkers because of the machinery required to provide heat and pressure.
- Phenol Formaldehyde must be used in a well ventilated area because uncured resin is irritating and can be toxic. Once cured it outgasses formaldehyde. Outgassing is less than in urea formaldehyde adhesives though, and diminishes considerably with time.
- It is darkly coloured and can be seen in the seam of marine and exterior plywood.
- It needs good contact and pressure to make a solid bond and it is not a very good gap filling material.
- It is more expensive than Urea Formaldehyde glue which explains why it is not used for all plywood.
So can Phenol Formaldehyde be used in Boatbuilding?
It is widely used in boatbuilding but only to put together the plywood that is supplied. Since it requires heat and pressure few wood workers are equipped to handle it.
Resorcinol glue is a very close relative of phenolic glues and it is available to woodworkers. It is strong, cures at room temperature and is highly waterproof. It is made from naturally occuring phenolic compounds.
See my page on Resorcinol Glue
I don't claim to be an expert. I'm not an engineer or a chemist. I make mistakes. This page is not a recommendation of products, it is for information and entertainment. IF you want to build a boat make sure you use the materials as instructed by the manufacturer. There are health concerns about most uncured resins and adhesives, so wear gloves and work in a well ventilated area, or wear a vapor mask. Do your homework and be safe.
email me if you find mistakes, I'll fix them and we'll all benefit: Christine