Glass Coat 1:1 Epoxy Finish

Australian made Glass Coat is an equal ratio two-part epoxy suitable for a thick high-gloss finish on timber and other materials,a clear filler for imperfections such as blind knot-holes and an embedding medium.

I trialed the finish on four timbers - Radiata Pine, Meranti, Merbau and Ghost Gum. All samples were sanded to a medium finish and then given a coat of polurethane.

The manufacturers of Class Coat, Craftsmart Australia, recommend sealing the surface of the wood with two coats of GlassCoat Premium Timber Sealer. There is no sanding between coats.The purpose of the sealer is to lock in or remove any air entrapped in the grain structure. A polyurethane or acrylic sealer can be used as a substitute if the Glass Coat Premium Timber Sealer is not available.

The sealer is worked into the wood with a brush. This can't be done with the GlassCoat as it is applied as a floodcoat, ie. simply poured on to the horizontal surface. I chose to use only a single coat to see if it made a difference.

After the wood is prepared and sealed, it is important to avoid contaminating the surface.This includes handlinq it with your fingers which may leave oily residue. Any contaminants may affect the finish or lead to delamination.

The edges of the surface to be treated should be masked with low tack masking tape (available from any paint or hardware store).

The tape should cover the sides, but not sit proud of the top. To achieve this I laid the samples upsidie down on a clean flat surface-a study desk or the kitchen table will do. The tape was applied by running it around the perimeter of the sample, keeping the lower edge just in contactwith the table top. When the sample was turned right side up, the result was a neat line flush with the top of the wood.

The manufacturers recommend that you work with Class Coat in an environment that is at least 23'C.I found that this was verv important. The weather had been unseasonably cold so I had to wait several days until it was warm enough in the workshop (barely 23C). The epoxy proved to be so viscous at this temperature that I would have preferred a hotter day. An option is to warm the epoxy containers in a pan of luke-warm water before use.

One reason I applied the epoxy in the unheated workshop was the risk of leaving a bad smell. The label says 'odourless'

but some of the earlier 1 :1 epoxy products on the market had such an irritating chemical smell that you had to leave the room (or building) after it was poured. I am very pleased to report that the Glass Coat is indeed virtually odour free. Nonetheless as with all chemicals it is important to work in a well-ventilated area.

When applying Glass Coat have several plastic cups handy (styrofoam tea cups work well). In addition to the one for mixing you'll need another for wet mixing sticks, etc, and others for mixing more epoxy.There's a wooden spatula supplied in the packaging for the plastic epoxy bottles but it's advisable to have extra mixing sticks on hand. even if vou use 'unused-' paddle pop sticks purchased from the local craft store. An important rule when working with epoxy is to always use fresh equipment when mixing additional material, to avoid contamination.

Work out your volumes. According to the instruction, 50mls of each (100mls total) should cover 300mm. I worked off this figure and had a good result. However, the epoxy is so viscous that I expect the volume applied could be increased by up to, say, 50% for a thicker coating, if desired.

Pour the fluid from one bottle into the plastic cup and replace the lid on the bottle. Swapping the bottle lids is an easy way to cross-contaminate and the bottles ruin the product.To avoid this,I never have both lids off at the same time.

Check how much is in the cup by examining the level in the bottle. There's identical text on the bottles so there are plenty of reference points from which to work. Give the fluid a few seconds to drain back into the bottle so that you can take an accurate reading. Ensuring that you have equal volumes in the cup is part of the 'trick' of working with 1:1 epoxy.

Pour the contents of the second bottle into the cup. Try to avoid losing fluid down the outside of the threaded top when you pour as this will also affect the accuracy of your measuring.

When satisfied, mix the two parts in the cup well. Both parts are crystal clear so there is no colour change to tell you when they are mixed. lf you've tried baking, you will know that it takes a fair amount of mixing to thoroughly combine the

the two ingredients.

Once this is done, you have less than 20 minutes before the finish starts to set up. This is plenty of time for small pieces but for something large such as a table top, you will need extra hands.

When I poured the epoxy onto the samples,it was very viscous,something I attributed to the low ambient temperature.The fluid was slowly but self-leveling to speed up the process, | 'teased' it to the edges and into the corners with the tip of the mixing spatula. A paint brush can be used to spread the epoxy but take care not to leave ripple marks in the finished surface.

Unlike paint which tends to run down the sides of the wood, I found with the epoxy that I was able to work it right up to the edge without any runs, due to the thick meniscus. However, during the curing process some epoxy did seep under the masking tape in places, presumably because I had not sealed the sides. This had no effect on the uniform thickness of

the epoxy along the arisses. There were two tvpes of bubbles that appeared in the finish. Those that were formed during the mixing lay suspended in the coating. l've used 1:1 epoxies before and prefer to use a small LPC blowtorch carefully waved across the top of the surface to remove these bubbles. The air heats up and the bubbles quickly float to the surface to 'pop'. A butane torch or other similar tool with a naked flame can be used and the heat should be kept 150mm or so above the epoxy. In spite of its chemical nature, epoxy will start to scorch rather than burn and so long as you back off the heat when there is any evidence of fumes or the onset of discolouration, this is a safe and effective method of removing bubbles in the fluid.

Don't use a hair dryer or heat gun as the air movement will cause rippling in the finished surface. Other methods that are suggested for shifting the trapped air are blowing across the surlace wilh a straw or using a pin to prick lhe bubble. I tried the first method once and don't recommend it unless you are working on a very small area or have very large lungs. The second method works for a few bubbles but it is far too time-consuming for larger areas. On the Pine and to a lesser extent the Meranti there were a few bubbles underneath the coating, ie. ones that were sitting

on the surface of the timber rather than suspended in the fluid. These would not rise to the surface when the flame was applied and had to be pricked with a pin. The results suggest that sealing with two coats of sealer is more important when working with the more open-grained timbers, where air is more likely to be trapped in irregularities in the surface. While the epoxy starts to set after 20 minutes it takes hours to harden and is best left alone lor 24 hours in a dust-free environment. Glass Coat is an easy product to work with, so long as you follow the basic rules of preparing the surface, mixing the epoxy well, having the correct 1:1-ratio, etc. However a level of skill and familiarity is required before tackling larger prolecti. It is advisable lo start on small samples or items and progress to larger applications. The epoxy is well cured in say 36-48 hours, but it takes several weeks to achieve full curing. Only then is it fully hardened and heat-resistant. In addition to providing a durable high gloss surface, Glass Coat-can also be used for a heat-resistant finish in various applications

such as kitchen workbenches. Glass Coat can be cleaned with soap and water, but abrasives and strong solvents should be avoided. For further information on Glass Coat or details of your nearest stockist, phone Craftsmart Australia Pty Ltd on 03 9558 9477 or visit www.chemquest.com.au.