Hot melt systems: Why is my glue this colour?
After you’ve finished reading this article, we suggest visiting the production line, and taking a good look inside your hot melt tanks and parts. If you see a light yellow-coloured or clear adhesive, that's great. If the adhesive has started to discolour, you are beginning to cook the adhesive.
Here are a couple more images for reference:
As you can see, this glue has already begun to jellify. The later stages of this degradation of adhesive is that black, tar-like substance you can see coating hot melt parts here.
Depending upon your grade of hot melt adhesive, it can arrive as either honey-coloured or clear in the box. But as it heats up, the colour will darken as the components of the hot melt start to cook and degrade. So what exactly is too dark a colour for adhesive? Where do we draw the line?
This chart offers a visual representation of the gradual cooking of overheated adhesive.
As a rule of thumb, once your glue starts to look any darker than light honey, you don’t want it to darken further. Make good use of the standby button on your hot melt tank to prevent excessive heating and cooking of the glue in periods of downtime. In an ideal situation, the rule of thumb is to top up your hot melt tanks little and often. This relies on the operative adhering to this rule, and in order to eliminate operative errors, an auto-feed system can be installed.
You can fill out our contact form here if you would like more information on auto-feed systems or to tell us about the equipment you need cleaning and we will call you back to discuss in more detail. In the meantime, please feel free to browse our blog to see what other tips we have to keep your hot melt equipment running in tip top shape!
