Adhesion Issues Tips & Techniques

Poor adhesion can also be described as wet spots on the side of the glass and looks like a ‘wet’ appearance in parts. First, it’s worth pointing out that this is a very common occurrence when making candles in glassware, particularly with clear glasses whereby it’s easily visible, and natural waxes can also be more prone to it. If you do some research, you will find even some of the most expensive soy wax candles from large manufacturers have the same result. You are certainly not doing something wrong if you do see some container adhesion and it most certainly will not affect the way the candle burns.

The reason it happens is basically due to the minor shrinkage that occurs when the wax is cooling and also the minor imperfections on the inside of any glassware surface. The wax will pull away from the glass in some areas and be left stuck to the side in others.


As mentioned before, by no means is container adhesion a product problem. However, it is acknowledged that visually the candle does not look perfect and you may have customers who would prefer not to have it. So, what are the options? Well, the most obvious solution is to use frosted glasses instead of clear as container adhesion is not as noticeable. However, most people do enjoy the clear glasses and clear glasses do add that element of class to a candle. So let’s look at some other solutions for preventing poor adhesion in clear glasses for candle making with soy wax.

Hairdryer and heatgun

One particular process of preheating your glasses prior to pouring has worked well for a lot of customers. Depending on your manufacturing output, requirements will vary on what process you use. You can easily test this by using a hair dryer or heat gun to give your glass some initial heat, which reduces the temperature differential when you pour in the warm molten wax. You could also preheat your glasses in the oven first, say on a tray before pouring. The glasses generally don’t need a lot of heat, so we are not talking about making the glasses hot to touch. Some larger scale manufacturers will run their glasses through a preheating chamber on conveyor belts prior to pouring and they say this does eliminate a lot of container adhesion problems.

However, it’s worth mentioning that container adhesion can be really hit and miss. One minute you are getting great results and the next batch you have different results. Like any testing, though, it’s essential to always document your pouring temperatures and ratios every time you make a batch of candles, so you can easily go back and troubleshoot and work out what was different and find out exactly what you did last time you poured. In some instances slowing the rate of cooling by allowing your candles to set in a much warmer environment may also help.

Another method some customers use is to blend in some of tart wax. This wax is designed to shrink, so the theory goes that a small amount blended in can shrink the wax enough away from the walls, so that there are no signs of container adhesion or 'wet spots', but the trick is not to shrink too much that the candle rattles around or falls out of the glass. This method is potentially better for glasses whereby the glass shape goes out and then comes back in at the top as the candle can never move around much or come out if it has shrunk. Every shape glass will be different and require different amounts of pillar wax, so will need some testing if you are wanting to try this method.

Another more advanced technique employed by some companies is to pour the candles using almost 100% tart wax in a set of glasses which become the moulds. So effectively you pour the candles first in these glass moulds. They will shrink and you take them out. You would generally use a rod or pin setup during the pouring process. Once the wax is removed from the glass and the rod has been pulled out, you can then feed in the wick, place some glue on the bottom of the wick tab and then place the wax and wick into a new glass, which will then become the finished product. By doing this you end up with no container adhesion as the candle has been poured and set in another glass. Generally most glasses have slight imperfections inside them so when you place the wax into the new glass it will not easily come out as it will not be the exact shape of the previous mould glass. The trick in setting up your pin system in the glasses is to allow for the wick to be placed into them later. Obviously this will only work in glasses that are straight walled or taper out larger at the top than the bottom. This would be for an experienced manufacturer wanting to develop a long-term system to have perfect candles in respect of container adhesion.

We hope this gives you some insight into the widespread results from making candles in clear glasses and the sometimes intricate nature of pursuing the goal of making perfect candles.