What's the Point of An Epoxy Seal Coat?
One of the most common questions asked when doing epoxy is; why can’t I just pour the epoxy over my surface? Well, in some cases you can, in most cases, you definitely would regret not applying a seal coat before attempting your flood coat. For surfaces like laminate, formica, and other non-porous substrates, the seal coat isn’t necessary as the epoxy can work fine when applied as only a flood coat. However, when it comes to substrates like wood, concrete, and tiles with grout lines, they all have one thing in common: they are porous and filled with trapped air that will try to escape into your flood coat once it is poured. Since no one would be happy with a bubble filled epoxy surface, it’s the user’s job to ensure the surface is properly seal coated to prevent this from happening. In this blog we'll go over why or why not you should apply a seal coat of epoxy to your surface.
What is an epoxy seal coat and what’s the point of it?
A seal coat is a thin layer of resin, brushed over the surface evenly prior to mixing and pouring the flood coats. Sometimes one seal coat is perfect and will produce great results, other times you will need to apply 2 to 3 brushed on seal coats before moving on as one seal coat may not be able to serve it’s purpose properly.
A seal coat serves two main purposes:
1. Sealing a porous surface to prevent air bubbles from escaping into the epoxy flood coat.
2. Providing a tacky layer of resin for the flood coat to easily bond with.
How do you know if your surface need an epoxy seal coat?
For the majority of projects, it’s pretty simple to determine if you need a seal coat. If you’re pouring over anything made of wood or concrete, then you should always do one seal coat at the very least. Some surfaces may not look porous, but actually are. Granite and marble are two examples of this. While they may appear smooth and solid, they do contain pours that can soak up liquids and can release air bubbles if not properly seal coated with epoxy first. You can test this out for yourself by pouring a small amount of water onto your surface, if it get’s absorbed and darkens in that area, then you know it’s porous and is absorbing that liquid.
What’s the point of multiple seal coats?
For extremely porous wood, such as reclaimed barn wood that is covered in things like cracks, knotholes, etc. require extra preparation before flood coating. If you only did one seal coat over a substrate like this, it would simply be absorbed directly into the wood, and wouldn’t provide a proper seal over the surface to prevent bubbling issues from arising later. This is why we highly recommend doing 2 to 3 total seal coats, spaced out every 4 to 6 hours, to ensure you have a solid seal spread evenly over your surface that won’t allow any bubbling to occur.
What happens if you do not seal coat a wood surface?
Despite knowing everything about seal coating, sometimes beginner epoxy users do not heed our warnings and decide they’re not interested in any extra work aside from pouring the epoxy directly on the surface and calling it a day. When this happens, you can not only expect thousands of micro bubbles to constantly be released into the flood coat, but you will often be left with low spots in your surface where the epoxy flood coat was absorbed almost entirely by the wood. You can’t expect to have a 1/8” glass like layer of resin over your surface, if your surface is actively absorbing the epoxy and preventing it from doing it’s job properly. While our Bar & Table Top Epoxy Resin is an amazing product and does a lot of the work on it’s own, it’s ultimately up to the user to ensure it iss applied properly in order for it to cure and protect your surface with the maximum durability as it’s designed to do.
What about any bubbles in my seal coat?
When you pour an epoxy flood coat, you need to have a heat gun on hand to pop any bubbles that you have mixed into the resin after it’s poured. These bubbles are easy to pop by waving the heat gun over your surface within the first 15-20 minutes after it’s poured. However, the seal coat does not require this. You do not need to worry about popping air bubbles in the seal coat as if it’s applied correctly, it will do it’s job and soak into and seal the surface to prevent any trapped air from getting through it and into your resin flood coat.
What are the best tools for mixing and applying a seal coat of epoxy resin?
Unlike the flood coat, which can be mixed in gallon sized batches at a time, you always want to mix smaller sized batches for the seal coat, and will need to do this by hand. To do this you’ll need the proper mixing tools and mixing containers. You’ll find the perfect products for this in the supplies section on our website. You can find stir sticks with holes machined out of them to allow for the easiest mixing experience, without drawing too much air into the mixture of resin and hardener. You’ll also find smaller one quart containers, which include easy to read measurements on the sides that help the user achieve the proper 1 to 1 mixing ratio by volume.
It’s best to mix smaller amounts such as 8oz and 8oz or 16oz and 16oz for the seal coat, as you do not want mixed epoxy sitting inside a container for longer than 5 minutes. The epoxy activates once mixed and cures by generating heat, when this heat is trapped inside a container, it can cause rapid curing, which is why smaller batches work best as it’s easier to brush a smaller amount of resin over your surface in time.
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