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Mirror Coat, How Much Do I Need - System Three

Introduction To MirrorCoat

MirrorCoat® is a two-part epoxy resin product specially designed to create a high-gloss, clear decorative coating for wood and other materials. MirrorCoat will also protect the surface from spills and denting. Products like this are sometimes referred to as bartop coatings. But unlike most bartop coatings, MirrorCoat is mixed in the ratio of two parts of resin to one part of hardener by volume. This 2:1 ratio provides a harder and more heat-resistant coating than a typical 1:1 material. MirrorCoat, like all epoxy resin coatings, will yellow slightly over time. Where the material will be exposed to considerable sunshine we recommend using a clear coating containing UV-absorbers. System Three manufactures two such products, Spar Urethane Varnish, and WR-LPU polyurethane. Do not use MirrorCoat epoxy over white backgrounds unless noticeable yellowing is acceptable.

Understanding the MirrorCoat Process

MirrorCoat is usually applied to porous surfaces. Like any liquid, it will try to fl ow into the nooks and crannies and displace any air that is present. During this process the epoxy is curing, and will gradually get thicker until it becomes rubbery and fi nally solid. Any displaced air will try to rise through the thickening liquid. Air bubbles may not be able to rise to the surface and pop before the material cures. If this happens bubbles will be left in the cured coating. Minimize this problem by applying the material in two coats as described below. Apply MirrorCoat with a natural bristle brush on vertical surfaces. Multiple coats will be required to build up a thickness equal to the poured-on layer. New coats can be applied as soon as the current coat has gelled. MirrorCoat will attempt to level itself as it cures. Ensure the surface is level or MirrorCoat will pool on the lower portion and run off the surface. Excess Mirrorcoat can drip and run over the edge of the project. Use a natural bristle brush to spread out the runs once the material stops dripping. Always use a plastic drop cloth on the fl oor when working with this product. Any airborne dust that lands on a curing epoxy surface will fl oat and leave a small bump in the cured coating. To minimize this problem work as much as possible in a dust-free environment. For best results vacuum the area so that dust isn't stirred up while applying MirrorCoat. Clean the surface using lint free rags dampened with paint thinner. Allow all the thinner to evaporate before application. Avoid tack cloths as they leave a waxy residue, which may interfere with the epoxy bond. After application, turn off fans and air conditioning, and leave the room so that the air in the room stays as still and dust-free as possible. If dust can't be eliminated during application, MirrorCoat may be sanded and polished to a high gloss after curing is complete.

System Three: How Much Mirror Coat Do I Need?

Our MirrorCoat (bar or tabletop epoxy) literature mentions a minimum coverage rate of 1.5 fluid ounces of mixed epoxy per square foot. Ignoring substrate absorption this makes a film about 0.020 inches (20 mils) thick. Dry paint film is typically 2 mils thick. So why do we recommend that MirrorCoat be ten times thicker?

The reason is that a film of MirrorCoat epoxy must be thick enough so that proper flow and leveling occur. Gravity helps thick films overcome surface tension effects that predominate in thinner films. If you brush MirrorCoat on a substrate you are apt to get brush mark "highs and lows" in the cured coating when the film thickness is less than 20 mils.

So, the minimum amount of MirrorCoat you should use is 1.5 fluid ounces per square foot. Add about ten percent more to do the seal coat. If you are coating a bar top 2.5 feet wide by 12 feet long you'll need a quart and a half kit (One quart of resin plus one pint of hardener.) Here's the math: 2.5 times 12 equals 30 square feet. 30 times 1.5 fluid ounces equals 45 fluid ounces. One quart equals 32 fluid ounces, one pint equals 16 fluid ounces, and thus, the kit equals 48 fluid ounces, which is within spitting distance of 45 fluid ounces.

So, how much do you need if you are coating the same bar with an eighth of an inch? Well, an eighth inch is 125 mils (1 divided by 8 times 1000). If it takes 48 fluid ounces to do 20 mils then it will take about six times this much to do 125 mils. Six times 48 is 288 fluid ounces. There are 128 fluid ounces in a gallon. Dividing 288 by 128 yields 2.25 gallons - or, 1.5 gallons of resin and .75 gallons of hardener. There is no kit like this. One could get a 1.5-gallon and a three-quart kit and hit it right on the nose. But, the cost of a three-gallon kit is slightly less than this so we'd go for the larger kit.

There is a more accurate way to figure this: 30 square feet times 144 (square inches/square foot) times 0.125 inches (1/8 inch thick) equals a required volume of 540 cubic inches. There are 231 cubic inches in a gallon. Dividing 540 by 231 equals 2.34 gallons - again the three-gallon kit is the right amount to buy especially when the seal coat is added.

Methods And Tips For Applying Mirrorcoat

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