8 января, 2016 
Pokraskin Small air bubbles in the joint may not affect the overall strength of the joint but can cause leaks or in some cases be an aesthetic issue.
These bubbles may originate from the adhesive packaging but can also be due to shrinkage of the adhesive as it cures. Most of the acrylic-based adhesives will shrink on cure slightly whilst epoxies tend to show lower shrinkage. Applying smaller volumes of adhesive will minimise the shrinkage voids and so in some applications it may be necessary to apply the adhesive in two ‘lots’.
The dispensing system may also be the cause of bubbles: any liquid will absorb air in solution when it is pressurised and this air is released in the form of bubbles when the liquid adhesive returns to atmospheric pressure. The best example of this is a bottle of lemonade. The lemonade appears perfectly clear until such time when the top is unscrewed and the pressure is released and immediately bubbles will appear
in the liquid. The same effect can happen to a bottle of adhesive in a pressurised vessel. Inside the pressure pot, the adhesive will slowly absorb air and so when the adhesive is dispensed down the tubing, this air will be released in the form of bubbles. These bubbles in turn can cause problems in terms of voids in the joint or ‘run-on’ at the nozzle tip due to the build-up of air in the dispense valve. Reducing the adhesive pressure and using gravity-fed systems will minimise the effect of bubbles.
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