Using Two Pack Paint
Whether you’re an experienced painter, or you’re new to this area, it’s important to know how to use two pack paint. Often even the most experienced painters get it wrong, and it can lead to messy results. The basics of a two pack paint is that there are two components that you mix together prior to application. When the two components have been mixed it starts a chemical reaction that allows the paint to eventually dry. Simple enough, and very similar to things like araldite glue that a lot of us are familiar with.
However there are variances within products, and pitfalls that are easy to fall into: especially if you’re doing the job in a hurry.
Read the Datasheet:
The most basic piece of advice that I can give is to read the Datasheet for the product before you use it. Most of the datasheets for our products are on our website (click the Downloads button within a product). if a datasheet isn’t on our website then we can find it and send it to you.
The datasheets not only give you instructions on how best to use and apply the products, but they also give crucial information about mixing two components. The three main things to look for are: the length of time recommended to mix the product; the potlife after mixing the two components; and also whether or not an induction time is needed.
Mixing the product:
Both components need to be stirred separately, before being mixed together. Mixing manually is never recommended for 2 pack products, as it’s near impossible to ensure that it has all been mixed and you’re likely to get a patchy finish. you need to use a mixer and a power drill set to a low speed
When mixing with a mechanical mixer you need to be sure that it is set at a low speed. It may be tempting to crank up the speed to try and mix it faster, but the heat that will be generated from mixing faster would cause issues further down the line. The heat affects the reaction between the base and activator, and has a detrimental impact on the curing.
After the products are mixed, and the chemical reaction has started, sometimes an exothermic reaction happens and the paint gets hot. But don’t worry, that’s perfectly normal. As long as the mixing itself was done slowly it’s all fine.
Pot life after mixing:
Once the base and the activator have been mixed then it initiates the chemical reaction that causes it to cure. So once the two components have been mixed you have a limited amount of time to apply it before it has hardened too much. Often it is recommended to keep stirring at different intervals throughout to give you some extra time to apply the whole mix.
Usually the pot life is only a couple of hours, so make sure you are ready to do the work before you mix the components together.
If the pot life is an issue because you need to do more than one coat then you may be able to split the pack. But you need to ensure that you keep the ratio of base to activator correct. These ratios are usually on the datasheets.
Sometimes a product will have an induction time in with the instructions. this is basically a short period of time to leave the paint to begin it’s chemical reaction before you start to apply it. Some epoxy coatings require a specified induction time in order to fully “compatibilize”, which means that the components have bonded and stabilised.
If the specified induction time is not followed then it can lead to further issues, such as: a lower gloss level, yellowing, blushing, colour variation and more.
Here are some of the most common issues that we come across when people use two pack paints. By knowing them, you can avoid falling down the same pitfalls because it’s all easy when you know how!
- Separating the mix, and miscalculating.
- It’s common for people to want to use part of the tin now and part later. Where this becomes more complicated is that if you’re using a two pack paint you need to keep the ratio of base to activator the same. Usually the ratios are on the datasheets, and as long as they’re followed then there wont be any issues. but if you are struggling then our Technical team can help you (01902 710057).
- Separating the mix can be done by either weight or by volume, but make sure you’re using the one consistent with the datasheet.
- If you think you may have gotten the ratios wrong then there are a few ways to figure it out by the issues you’re having with the finish.
- Undercatalyzed Films:
- May not fully cure.
- May be soft or gummy.
- Overcatalyzed films:
- May be hard and brittle.
- Discolouration, yellowing and reduced performance.
- Undercatalyzed Films:
- Forgetting to mix them together.
- Of all of the mistakes, this is the most difficult one to fix. If you have applied one of the components, then applying the other one over the top, or trying to mix it on the surface won’t fix it. The whole thing would have to come up and start again. So you really need to make sure you get this part right the first time!
- Letting the paint harden before you’ve got it all applied.
- This can be from either not getting the work done fast enough or from not stirring the product intermittently when applying.
- Once the paint is too far cured then there’s nothing that we can do to bring it back. So if the job isn’t finished and the paint has gone hard you’re going to need some more paint.
If it’s not done properly. . .
There are several things that can happen if a two pack paint isn’t mixed properly. A few of them I have mentioned already, but here are the main ones to look out for.
- If the parts aren’t mixed together properly then some parts of the surface won’t dry at all. Patches of it may dry, but there will be some bits that haven’t reacted. The only thing to do if this happens is unfortunately to start again.
- If the induction time was not followed then there are a good few issues that can arise. They are mostly aesthetic, but nonetheless problematic.
- These issues include: lower gloss level, blushing, yellowing, colour variance etc.
The best thing to do is always to talk to us if you have any doubts or questions. We have over 30 years of experience with paint in our technical team, so use their knowledge to your advantage.