Laminating with Polyester General Purpose Resin and Chopped Strand Matting needs to be undertaken correctly if you are to create a strong, waterproof layer or Laminate. This guide will walk through the basic techniques needed to Laminate with confidence while understanding the basic process. We are going to laminate a small area of 600g CSM with a standard general purpose polyester resin onto a standard OSB3 Roofing Board for our example.
Materials We Used
Preparation
Make sure that your OSB3 Board is clean and dry and clear of any debris. If unsure wipe down with an acetone wipe to remove any grease or dirt. Prepare your materials and make sure they are close at hand. Place the Chopped Strand Matting (also known as CSM) on the board.
Adding Catalyst
In average working temperatures you will be adding 2% catalyst to the resin by weight. At this ratio you will need 6 grams of catalyst for the 300 grams of resin. The catalyst can be added to the resin in the 550ml mixing cup and stirred into your resin. Mixing for 1 minute will be sufficient.
Wetting Out the CSM
With the resin catalised you are now ready wet out your CSM. Dip your 4 inch roller into the resin and with a loaded roller head apply the resin diretcly to the CSM. The matting will naturally want to absorb the resin so working reasonably quickly apply an even coverage over the CSM adding additional resin to your roller as you go.
You will notice that the Matting will start to become translucent with the OSB3 Board now visible through the Resin and Matting. Make sure you wet out the entire Matting area paying attention to the edges and corners. Resin pooling on the surface of your matting does mean you have applied to much and excess can easily be removed with your empty roller head.
Consolidation
Consolidation is the process by which air is driven out of the body of the matting so that the CSM is completely “wetted out” using a Paddle Roller. This is the most important part of the lamination process. Any small pockets of air can result in a loss of strength and failure of the waterproof membrane that you are creating. Work the Paddle Roller over the whole body of Matting in a logical and deliberate way applying even pressure to the head of the Paddle Roller. This process makes sure the CSM is “Fully Wetted Out”. Again, pay attention to corners and the edging of the matting.
Removing Small Air Pockets
Areas of your matting which have small air pockets are fairly easy to identify during the Consolidation process and easy to remove. At this stage the matting will almost certainly be translucent and an area of air will look milky and almost opaque in comparison.
Work your paddle roller evenly over this area making several passes and you will see the area become completely translucent. You do not have to apply too much pressure and simply work the area until the milky opaque patch has disappeared.
The result should be an area of even resin distribution over the working area that is translucent in appearance.
Cure Times
Under normal working conditions your laminate will cure in around 30 to 40 minutes. Cure times vary significantly dependant on the ambient working temperatures. Once tacky you can add strength to your laminate by adding another matting layer following the same process as above. Alternatively your laminate can be Topcoated.