Phenolic plywood | Film-faced Concrete Shuttering plywood - Lceted

In this article, we will look at what phenolic plywood is, how it is made, and its application in the construction industry.

 

Phenolic Plywood Also known as Phenolic Film-Faced Concrete Shuttering Plywood, it is widely used in the construction industry to create wood moulds used for casting concrete when constructing concrete slabs and columns of buildings. One of the main advantages of using film-faced plywood for concrete moulding is that these boards are completely water-resistant, the concrete does not stick to their surface, and these plywood sheets can be reused after the concrete casting process is complete.

 

How phenolic plywood is made

Generally, phenolic plywood is waterproof type plywood with a phenolic film on its surface. In the final stage of the manufacturing process, a phenolic film is applied to the surface of the plywood. This is why it is also called Film Faced Plywood.

 

Manufacture Process of Phenolic Plywood

Step 1: Good quality timber logs acquired from hardwoods are used as raw material.

 

Step 2: Slices of wood veneers are obtained from these logs. For doing this, the timber logs are mounted on a machine, that rotates the logs about their longitudinal axis, while a cutter peels off layers from the log. These layers are the veneers.

 

Step 3: The veneers are graded according to quality, and stacked upon each other.

 

Step 4: Synthetic phenolic resin, made from phenol-formaldehyde, is evenly spread over the veneers to glue them together.

 

Step 5: The multiple layers of veneers (plies), arranged in alternating grain patterns, are then hot-pressed to form a strong and permanent bond.

 

Step 6: Preservative treatment is carried out on the plywood by adding appropriate chemicals.

 

Step 7: At the final stage, a very thin film of phenolic resin is applied to the surface of the plywood. This film is made by soaking and saturating a paper in phenolic resin. Once the resin has hardened, the paper becomes hard and the film is ready. The film is then hot pressed and melted onto the surface of the plywood, to achieve a smooth, hard finish.

 

Step 8: Glossy plywood is now ready for quality testing and transporting

 

The outer glossy surface of most phenolic plywood is usually dark red, although it can also be found in dark brown or black.

 

It is worth noting that decorative laminates are made using a similar process. For laminates, brown handmade paper soaked in phenolic resin and decorative paper soaked in transparent melamine resin are hot-pressed under high pressure, forming decorative laminate sheets that can be applied to the plywood as an overlay.

 

Quality tests for Phenolic plywood:

 

Like marine-grade plywood, quality tests for phenolic film faced shuttering plywood include water-resistant testing, during which sample pieces of plywood are immersed in boiling water for 72 hours, then removed and cooled in Coldwater. Still, wet pieces are tested for strength and make sure the outer phenolic layer does not deteriorate in any way.

 

The Indian Standard Specification Document for Concrete Shuttering Plywood is described in IS:4990.

Manufacturing companies that meet the recommended standards can obtain a certificate from the BIS (Bureau of Indian Standards) and then qualify to place a reliable ISI seal on their plywood sheets.

 

Quality tests for Phenolic plywood:

 

Similar to Marine grade plywood, the quality tests for phenolic film faced shuttering plywood also include water-resistance tests during which sample pieces of the plywood are submerged into boiling water for a period of 72 hours, and then removed and cooling by plunging into cold water. The still wet pieces are then tested for strength and also checked so as to confirm that the outer phenolic layer has not deteriorated in any manner.

 

The Indian Standard quality specification for Concrete Shuttering plywood is detailed in document IS:4990. Manufacturing companies who meet the prescribed quality standards can obtain a certificate from BIS (Bureau of Indian Standards), and then become eligible to put the trusted ISI mark on their plywood sheets.

 

Important properties of Phenolic plywood:

Durable: Concrete casting process involves alternative wet and dry conditions. The plywood must be durable to withstand these conditions.

 

High in Strength: Concrete is made by mixing cement, sand and crushed stone together with water. While the concrete cures and becomes hard it exerts a force on the shuttering plywood mould. So the plywood has to be strong to withstand these forces.

 

Reusable: The use of phenolic film fastened concrete shuttering plywood is advantageous because once the concrete casting process is complete the plywood shutters can be removed and these sheets reused elsewhere. To make this happen, however, the plywood sheets must be handled with care when setting up and removing the form so that they are reusable enough.

 

Shiny, glossy surface: The phenolic film provides the plywood with a very smooth glossy surface. This is a very useful characteristic in the case of concrete shutter work because the concrete does not stick to the plywood due to this smooth laminate film surface. The smooth film surface gives a smooth finish to the resulting concrete compared to other methods, and it does not require additional plastering of such concrete because it is already very smooth.

 

It should be noted here that not all concrete shutter plywood is film-faced. They also come in other types of plain or oiled. The ones with the phenolic image face are the sales.

 

Dimensionally stable: Since it is used in the manufacture of shutters used for casting concrete, its dimensions must be constant even under the extreme heat conditions that develop during concrete curing.

 

Expensive: Phenolic plywood is as expensive material as marine grade plywood because it is made to meet high-quality standards compared to furniture-grade plywood.

 

Phenolic plywood is durable and best serves its purpose when the sheets are well maintained. Avoiding scratches, wear and tear, cleaning the surface, and applying mould-oil (parting oil) (fritting oil) to the surface all contribute to its repeated use to enhance its quality and make it more durable.

 

Even after the concrete has been used repeatedly for casting, it can still be used to make good quality utility furniture such as work-benches, table-tops and outdoor woodwork. For other applications like this, buying used phenolic plywood can be much less expensive because the same type can be purchased at a significantly lower price than buying brand new plywood.

 

FAQ

What is the difference between phenolic board and plywood?

The phenolic surface offers many properties not found in other types of plywood products. In different types of plywood, phenolic provides a rough and very stable surface. The phenolic surface resists cracks and splits well from fasteners so it can be used in concrete formwork.

 

What is phenolic plywood used for?

Even after the concrete has been used repeatedly for casting, it can still be used to make good quality utility furniture such as work-benches, table-tops and outdoor woodwork.

 

Can phenolic boards get wet?

Although it is suitable for concrete forms, it is not suitable for use in the construction of furniture or store equipment. The edges of this board are painted with oil-based paint, which is somewhat waterproof.

 

What is 'Phenolic bonded plywood'?

Phenolic bonded plywood would simply mean plywood that has been made using synthetic phenolic resins

 

How many times can you use the phenolic board?

For casting concrete we can use around 30 to 50 times but it depends on how you maintain

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