Avoiding Bubbles In Epoxy Applications
Bubble formation in epoxy coatings is more times than not the result of air expanding within a porous substrate and releasing into the freshly applied epoxy. To avoid this issue consider the following:
- Avoid applying epoxy on a surface that is being heated either by the sun or a conventional heater. When possible, wait till the substrate has stabilized in temperature or is in the process of cooling before applying epoxy.
The first coat of epoxy applied on raw wood should be very thin. Use a 1/8" foam roller and apply the epoxy at 1/2 fluid oz. per sq. ft. Some ultra-porous substrates may require a second seal coat. If a seal coat is applied too thick, persistent bubbles which are difficult to remove will result.
- Bubbles can also be present over a fully sealed substrate. These bubbles are the result of entrained air from mixing or the product from brushing or rolling. Most of the time these bubbles will pop naturally. Stubborn bubbles can be popped by lightly dragging a brush over the surface of the epoxy. A propane torch can be used judiciously by holding the flame 6-8" from the surface while moving quickly back and forth. Do not overwork the bubbles with the torch as scorching of the epoxy can occur.
How do I clean up resin, hardener, and any uncured epoxy?
Solvents such as lacquer thinner, denatured alcohol, and acetone may used for cleaning spilled resin and hardener. Lacquer thinner is the best choice for cleaning any mixed uncured epoxy.
How to remove cured epoxy.
Cured epoxy can be successfully removed from most substrates by using a quality paint and epoxy stripper. However, care should be exercised as the stripper can damage other surfaces. Carefully follow the manufactures instructions and recommendations.
How to fix orange peel in an epoxy coating.
To help fix the appearance of orange peeling, please allow the existing epoxy to cure for about 48 hours or until hard enough for sanding. Block sand flat using 120-150 grit, vacuum sanding dust and wipe clean with denatured alcohol. You may then re-coat.
The Part B hardener has gotten darker over time. Can I still use it?
Probably. Hardeners yellow and darken over time due to contact with air and sunlight. This does not affect their performance. If the batch date is older than 3 years, to satisfy yourself do a small test and make sure it cures properly. Batch code: X(YEAR) XX(MONTH) XX(DAY) X (INTERNAL CODE).
Get rid of bubbles in an epoxy coating.
Two methods can be used to rid of bubbles in an epoxy coating:
1. Roll and Tip Method: Bubbles that persist in the coating can be broken with a disposable bristle brush by lightly dragging it across the surface after rolling the product out.
2. Propane Torch: Quickly and lightly fan 6-8 inches above the uncured surface with a propane torch to accomplish bubble popping with greater speed. Avoid overheating an area as this could cause the epoxy film to pull away from the surface creating craters.
NOTE: When coating a porous surface like concrete or wood, overheating to pop bubbles with a torch can cause the expansion of any air in the pores of the substrate and can make the bubble situation worse.
Why didn't the epoxy cure?
There are two common reasons why the epoxy didn't cure: incorrect measuring and incomplete mixing. Measuring and mixing is really easy with most System Three® epoxy systems because they mix at a 2:1 or 1:1 volume ratio, but this doesn’t mean you don’t have to pay attention to what you’re doing. First , read the label or Technical Data Sheet to see what the correct ratio is for the product you are using. Customers will call our Technical Support line suggesting that something is wrong with the epoxy because it didn’t cure properly. We know of no situation where properly-mixed resin/hardener has gone bad or has been contaminated and wouldn’t cure. In the majority of cases, it turns out that the batch was either incorrectly measured or insufficiently mixed. Epoxy chemistry just will not allow it to work any other way.
If you’re working on a project that requires you mix many small resin batches, develop a measuring technique that is sufficiently accurate and stay with it. Doing it the same way each time will minimize the chance for error.
The Part A resin has hardened and turned white. Can I still use it?
Yes. The white solid or haziness is a mass of resin crystals. Crystallized resin will not cure properly. To bring the resin back to a usable state, heat the bottle up in a water bath above 125 degrees F until the resin clears up. It will then be ready for use.