Mixing CPES is relatively easy, but following these instructions will help if it’s your first time with the product.
You have to mix CPES because it is a two part product
Getting CPES from it’s tins
Before you can get it out of the tins, you will find two metal inner seals underneath the wadded caps. Driving a nail or similar through the middle of the innerseals, then levering the seal out with the nail or a screwdriver is the easiest way to remove them. Please wear gloves to avoid getting either component onto your hands.
To pour CPES from the tins into your measuring vessel, it’s normally (Especially with full tins, less important as you use the product) easiest to pour with the neck high on the tin. This is with the neck at the top on the 5L tins, the tin vertical with the neck in the middle on the 1L and 500ml tins. This position allows air to easily flow back into the tin, and allows the CPES to pour smoothly rather than gloop in bursts.
Why do I have to mix CPES?
Smiths CPES is an epoxy resin. That means it is a two part polymer and consequently CPES comes in two seperate cans. Their total volume adds up to the quantity that you purchased. The spines of the cans are clearly labelled A and B. The shelf life of CPES in it’s cans is excellent, as it does not start to cure until it is mixed.
If you do not mix it – it will not set.
- Part A – is a pale yellow colour
- Part B – is a clear liquid
Mix CPES 1:1 by volume.
Mix by weight using 98 parts A by weight to 100 parts B for both Cold and Warm formula.
Once mixed CPES should be a transluscent pale yellow liquid.
The below photo’s show the two amounts in the photo’s above combined then stirred vigorously to mix the components. The mixed CPES will go cloudy when initially combined and should then clear once stirred to thoroughly combine.
It should NOT be cloudy, like the photographs below.
Mix CPES at a relatively warm temperature
We have had a few instances where CPES has mixed milky like the above. Mixed like this it will not work.
We traced this problem to a batch of one raw material which has been used in a few of our batches of product. This is an intermittent problem – and we have discovered that it is very temperature dependent and is completely curable when mixing.
We recommend warming your CPES up to house temperature (~20 centigrade) prior to mixing it.
If your CPES is stored in the cold and mixed there – it might mix to a cloudy blend like the below photographs – these were mixed at around 10 – 12 centigrade. This slightly cloudy mix will in fact cure properly but it’s hard to tell milky from cloudy.
We warmed the mix by by putting the jug into a pot of hot water for 2 minutes and stirring. Do not allow any of the water to get into your CPES. The mixed CPES clarified completely, and is now perfect. It’s always easier to warm the containers overnight by storing them in warm ambient surroundings however.
We chilled CPES to freezing, mixed it and then clarified it by warming in this worst case scenario video.
Please contact us immediately if your CPES appears milky and you cannot get it to clarify by warming it. Do not use it. Please phone 01732 824 700 or use the contact form on this website.
Mixing CPES – what in?
Mixing CPES safely in glass, metal or food grade plastic containers (HDPE, PP or similar plastics will be fine).
Measuring CPES
Whilst you can use a graduated measuring vessel to measure parts A and B, it is just as effective to:
- Pour an amount of one part into a container
- Mark the level on the container with a marker pen or tape
- Decant the first part into the mixing container
- Fill the measuring container to the marked line with the second part
- Decant that into the mixing container
- Mix thoroughly in the mixing container
This won’t leave you with a contaminated measuring jug, just a jam jar or similar that you can simply throw away.
We used drinking cups with lines cast into them which we used to measure identical amounts of part A and B in the p[hotos accompanying this mixing CPES demonstration.