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How to Mix Adhesives - How Much Hardener?

It almost goes without saying that the more experience you gain working with products, the more easily it becomes. Adhesives, like many other products, sometime require mixing. This is particularly true if you use bi-component polyester sold in cans. If you have ever seen a seasoned stone professional mix up adhesive without weighing the components and wondered if it is possible to learn how to do it. Keep reading. In this short how to we are going to cover how much hardener to use. The video above demonstrates how to mix Tixo. The secret is simple really.

Getting the Ratio Right

The secret to mixing in your hardener is to make sure you use the right ratio. But does that mean that it is always the same amount? Well, the atmospheric conditions will play a role in the mix ratio. So what is the recommended ratio to use?

The Mix ratio for glue to hardener is 97-95% glue and 3-5% hardener. Why the range? Well, as mentioned above, it is because there are allowances for variation. The the hotter the temperature, the less hardener you will need. So remember to dial down the amount of hardener just a bit when the temperature is up there. Another way to think of eyeballing the amount of hardener to glue is to use objects with which you are familiar as references. For example, one combination is a grape to an orange. So for every orange size lump of glue, you want to use a grape sized mass of hardener for mixing. But, as the video video mentions, 'in the summer time you are looking for small grapes'.

The most accurate way to get the correct ratio of glue to hardener is by measuring of course. However, with a little practice and a good guideline, you can get a good mix using this technique.

Other Considerations That 'Color' the Amounts

One thing to keep in mind too when you are mixing hardener into a polyester glue is that the ratios mentioned above should be used as your guide after the glue has been colored. Because you will be adding mass to the mixture when you combine the coloring paste, make sure to color the glue prior to mixing your hardener. So, your "orange" should already be colored when you add in the hardener. This will ensure that you get enough hardener into the mixture.

Allow for Slight Color Change

Adding hardener to polyester has a tendency to slightly darken the glue. As a result, the amount of coloring that gets mixed into the glue before the hardener should be slightly lighter in color than the actual color desired. This way, as the hardener gets added and the glue darkens a little, the desired color is achieved.

So, that's it. In summary, the following points should be kept in mind for how to mix hardener into polyester adhesive:

  • 95% to 97% glue to 3% to 5% hardener (A grape to an orange)
  • Use slightly less hardener in higher temperatures (smaller grapes in summer)
  • Color the glue prior to adding the hardener
  • Color the glue to be slightly lighter than the desired color since it will be a bit darker when the hardener is added.

Keeping these points in mind will assist you in getting the best polyester adhesive mix without experiencing the pitfalls of inaccurate mixing and/or coloring of your adhesive.