What is Ply Wood?

The term ‘ply wood refers’ to engineered boards of wood, that are manufactured by gluing multiple very thin sheets (veneers) of wood together. Each adjacent layer is rotated, often by 90 or 45 degrees, so the grain of the wood runs in different directions. This adds strength, reduces shrinkage and expansion, and greatly reduces the chance of the wood splitting when it is screwed through. The number of layers used depends on the final thickness of the board, and it is commonly available from suppliers in the UK in sizes ranging from 3.6 to 25 mm thick. A standard full size board is then 1220 wide by 2440 mm long. Smaller boards are available pre-cut and larger, thicker, and thinner boards can be bought, although generally take a bit more searching for.

The veneers of wood are cut from using a rotary lathe. This machine turns logs against a long very sharp blade that peels the wood in one continuous, or semi continuous roll. This technique of ‘peeling’ logs was invented by a guy called Immanuel Nobel in the mid 18 hundreds. One major positive factor for processing lumber in this way is how efficiently it uses up the wood from the tree, compared to milling it into planks.

All sorts of different types of wood are used to make ply. The choice people make depends on the requirements of the project the wood is to be used for, for example, if it’s for furniture, or a buildings structural construction, and whether its going to be used on the interior or exterior of a building. Sometimes the final outside layer of the wood will be an expensive, slow growing hardwood, such as walnut, cherry or oak. This is a very cost effective way to produce a fine finish for furniture or doors.

Once the veneers have been cut, they are dried and then glue is spread over the sheets. They are then layered and then pressed together while the glue dries. The types of glue used, once again vary, depending on the use of the plywood. Often for exterior used the glue is phenol-formaldehyde based and for interior use it is urea-formaldehyde based. One concern in using plywood is the potential off gassing of the glues chemicals long after production, and the possible health concerns that may arise because of this. Many manufacturers now use a low formaldehyde emitting glue, and some are experimenting with producing plywood using soy based glue. Large suppliers stock plywood that comes with an emissions rating, much like a paint’s Volatile Organic Chemical’s (VOC’s) rating. In my opinion this is something to be aware of.

In the plywood production process, once the sheets have been pressed and the glue has dried, the rough edges of the boards are cut away as they are trimmed to size, and then they are graded and packed, ready to be sent out to the wholesalers.

Plywood is produced all over the world from Finland to India and is classed as an environmentally sustainable building material. Certainly, if the manufacturers are using 100% traceable wood from responsibly managed forests, this section of the production is sustainable. As for the glues used, I will research further, and discuss in another blog post as this is extensive subject in itself and worthy of careful consideration.

There is no doubt that ply wood is a highly versatile building material with multiple uses, that simplifies many woodworking projects, compared to making the same thing from solid wood. If it is used correctly, that is; the right type for the job is selected, it is worked with care and finished suitably, it can be used to produce splendid items that should last for many, many years.

A New Stage for Mr Brown’s Pig

Mr Brown’s Pig is the performance name of Chris Brown, a committed storyteller, puppeteer and musician. He has been an inspiration to me for many years now, and I was delighted when he asked me to remake the framework and playboard of his puppet stage.

The dimensions and hinged folding design were to remain the same so that he could continue to use it in the same manner as the previous one, but he wanted it to be constructed sturdily enough to last the next twenty years. As he transports it by strapping it to the roof rack of his car, it is clearly subjected to a fair amount of wear and tear, and this durability requirement needed suitable consideration.

It was my opinion that the original stage had become rickety because the wooden frame had only been butt jointed and screwed together, and there was a lack of sufficient bracing. Also, I noticed that the hinges that allowed it to fold up were not particularly robust.

The answer was straight forward; cut decent sized mitred braces to support every right angle join, and to cut a shallow mortice and tenon for every joint, before gluing and screwing them from the reverse side into place.

I sourced some lovely brass hinges, which although were slightly too wide, were easy enough to trim to size with an angle grinder.

The playboard on the original stage was made from laminated MDF which  unsurprisingly was looking pretty tatty. I chose to use a piece of locally grown hemlock. I let it sit in my workshop for a month or so and then cut it to size, planed it smooth and rounded the edges with a router. We wanted to darken it as much as possible so it’s finished with a dark oak coloured wax.

The result is a robust frame and shiny playboard that should stand the test of time, and allow Mr Brown’s Pig to continue performing his excellent puppet shows for many years to come.

Mist Coat Roller Arm

Check out the state of my arm, it looks like I’m turning into an abominable snowman. Fortunately, this was not the case. On this particular job, I have been helping a builder, whose name is Geoff, to modernise the previously rather ugly, concrete ceilings in a flat in Clifton.

I’ve never done anything like this before, and so found the process intersting. It’s fairly straight forward really;

Evenly spaced wooden battens are screwed to the ceiling into predrilled holes with rawl plugs in them. Then plasterboards are screwed to wooden battens. To hold the 2.4m by 1.2m boards in place while we attached them properly, we made 2 T shaped frames from some extra wooden battens that reached to the ceiling. After as many whole boards as possible were put up, we measured and cut the rest to fit the spaces left over. Once this was done in each room, and remembering to cut a hole in the plasterboard for the lights to be reconnected by an electrician, a webbed tape called scrim was stuck over all the places where the plasterboard met plasterboard and over any points there were small gaps in between the wall.

Geoff then plastered all the ceilings, which he does a fantastic job of! How he does it, I don’t know, but they end up shiney and blemish free and painting them is a breeze. The mist coat is emulsion paint mixed with water, (this is the reason so much liquid sprays of the roller!) I think the idea being that the fresh plaster and plasterboard soak up the watery mix and this helps to achieve a better finish when the next coat of emulsion goes on.

Anyway, after that we redecorated the whole of the flat, and are just going to finish off glossing the woodwork tomorrow. It’s going to look lovely.