Laminating Timber

Laminating timber is nothing new as it has been done for many decades using various methods, what it gives us is the opportunity to take waste timber and make it larger or longer by laminating it for our purposes to suit any new projects we have, and by using waste timber we can turn simple boards into huge baulks of timber suitable for fencing posts, posts and rails, and even structural roof trusses; in fact we take small pieces of timber and laminate them to turn them into much larger pieces of timber for little expense, and certainly for much less than buying a single large piece of timber.

Laminating uses two main components, the timber or boards which are laminated together to form larger or longer boards, and the adhesive to bond them together as this not only adheres them as it also provides a large proportion of the structural element.

For the purposes of this explanation we shall be using pallets with all their boards removed and denailed and we shall assume they are 3" X 1/2" boards which are 3' long, and that they are free of splits and any other defects.

Our glue will be either D4 or expanding polyurethane glue which is referred to as PU and they will both be the 30 minute versions which dry in 30 minutes, but in reality it means that they have sufficient strength to have their clamps removed after 30 minutes, but we will leave them clamped for 24 hours as they both require a full 24 hours to achieve full strength. D4 is a resin based glue and has an expiry date on it and this should be checked at the time of purchase to ensure it has a long date on it, D4 is used on planed or smooth timber boards and they need to be dry and you may need to check the moisture content of the wood before gluing.

PU glue also has an expiry date on it and as it expands it fills small voids and fissures, this is used on the rough cut timber of general pallets and gives a much better bond than D4 as expanding PU actually expands, if you are working in hot and dry climates or with very dry wood you may need to activate the PU glue by using water from a hand type garden sprayer set to a very fine mist.

We begin by checking all our boards are straight and of equal length and width, any that are not are discarded, or if they have sufficient straight length we cut them to half the length of our full board as the half boards are used as end boards on alternative layers of our lamination.

We cover a flat surface with polythene or a couple of layers of cling film and lay one half board at one end and butt a full board up to it, we then butt another full board up to the end of the first full board and check them along their length to ensure our line of boards is straight, we can mark the bench polythene to give us a line or we can screw another piece of timber behind our line of boards to act as an alignment backstop as long as it is straight and has a covering of polythene to stop it sticking to our boards. We remove our half board and coat one end with PU and put it back into position, we then remove our other end full board and coat the end of that and put it back into position, all three boards on our first layer will be butt jointed with glue.

We take our next full board and cover one full face with glue and place it over our first half board and halfway over our first layer full board, we have begun our second layer, we take another full board and cover its face and one end with glue and butt this up to the end of the first full board on our second layer. At this point you can put panel pins through the second layer boards and into the first layer of boards to stop any sideways movement.

We now move onto layer three and we take our other half board and cover one face with glue and line it up with the end of our boards on layer two, we panel pin this down and take a full board and coat its face and one end and butt it up to our half board and panel pin it in position.

We move onto layer four and take a full board and coat one face with glue and set it into position and panel pin it down, this will give us a height of 2" at our flat end, and we then clamp the whole lot together and spray our glue joints with a fine mist of water to activate the PU glue if this is used and leave it overnight to cure.

We should now have layer one 2 1/2 boards long, layer two 2 boards long, layer 3 1 1/2 boards long, and layer 4 1 board long, and we should have one flat end while the other end should have steps 1/2 board shorter on each successive layer.

When you come back the following day you unclamp your boards and they should be bonded together and every joint should see the expanding PU seeping out, where your steps are you need to scrape this off with a sharp wood chisel until they are flush back to the wood, you slide your finished end off your work bench and support it with tressles and add tow more bull boards to your first layer by butt jointing them, two more boards to your second layer, two more boards to your third layer, and two more boards to your fourth layer. Clamp these new layers and activate your PU with another fine mist of water and leave overnight; you can continue with as many boards as you like until your length is sufficient and you add half boards to layers 1 and 3 to give you a flat end on your finished end.

Once you have finished you can scrape all the joints to remove any squeezed glue which has come out of your joints, or you can sand it off.

We use D4 or PU glue as once its cured it is waterproof and it can be stained or finished with wood treatments such as creosote or its substitutes and stood in the ground as fence posts, or anything else which is in contact with the ground.