Epoxy disasters: Common mixing mistakes that can lead to curing problems

mixing of epoxy

Most epoxy applicators at some point in their career will come across the nightmare of a stick or a tacky resinous floor. This is usually the result of improper curing between the epoxy resin and the corresponding hardener. There are several reasons why proper curing may not happen and in this article I want to focus on the mistakes that happen on project sites. Specifically mistakes that are due to improper epoxy mixing of the A and B component. Let’s have a look!

Proper mixing of the two epoxy paint components is very important
Proper mixing of the two epoxy paint components is very important

1. The not using an electrical mixer mistake. People seem to think that stirring the epoxy mixture with a stick or shaking the bucket will somehow create a uniform mix of the epoxy screed. Epoxy mixing is not like an acrylic emulsion. It actually requires significant power to be mixed in order to get a uniform product. Unless the quantity is very small (less than 2-3kg (4-5lbs) you must always use a mixer. If you don’t have an electrical mixer go get one. Otherwise don’t start the work.

2. The “a little bit of A and a little bit of B” mistake. The flooring team is close to finishing the project and there’s just a couple of square metres left to cover. There is obviously no need to open a full 15kg pack so instead you opt to take out partial quantities. Problem is if you don’t exactly measure the required quantity of A and B according to the manufacturers specs, but you do a guesstimate, you may get improper bonding. Epoxies allow for a very small margin error when measuring A and B quantities. A measuring error of more than 5-10% can cause major headaches. I have observed workers who have worked with other types of 2 component products like plasters and cements and seem to be complacent on the importance of measuring accuracy.

3. The Confusing weight with volume mistake. This mistake is an extension of the partial quantities mistake. The applicator reads on the product labeling that the per weight ratio of A:B is for example 5:1. So he automatically assumes that the volume ratio is the same and therefore measures 5 cups of A and one cup of B. Huge no-no! Hardeners tend to have lower densities than resin components. This means that an epoxy mixing system with a 5:1 weight ratio can easily become a 3:1 system if we measure per volume. Adding excessive hardeners to the mix could end you up with an oily finish.

4. The product expiration mistake. Epoxy products that are near or past their shelf life expiration tend to have the fillers sink to the bottom of the pack. This leads to the so called muddy bottom of the bucket. If you want to use the product you need to tip it into a new bucket and properly scrape the bottom. Then mix thoroughly before adding the B component. Otherwise the product stuck at the bottom will never be mixed in with the hardener properly, and you could get sticky patches on the floor.

5. The mixing of components from different products mistake. It never seems to surprise me how many times workers mix up components from different products. For example I often get people adding the B component of a primer to the A component of the paint. I have done everything in my power to minimize these mistakes happening (like changing the colors of the labels, increasing the letter size of the product name) but these mixups still happen. Such problems tend to occur on disorganized project sites, where no-one seems to be keeping track of supplies and what is going in and what goes out. Keep a properly organized site and appoint someone in charge of supplies!

Final point to remember! Every company has different products based on different formulations and different raw materials. Just because company A’s products works one way, don’t assume that company B is the same.

The following two tabs change content below.

Akis Apostolopoulos

General Manager at Ktisis
Akis has been involved in the manufacturing and application of industrial floor coatings for the past ten years. He runs learncoatings which is an online resource training professionals on the use of epoxy floors. He is also General Manager of Ktisis, a manufacturer of flooring and waterproofing coatings.

Latest posts by Akis Apostolopoulos (see all)