We all know you can powder coat metal but what about other materials such as glass? In order to powder coat an item there is really only one determining factor, it must be able to withstand 400ºF. Metal is one of the best materials to powder coat because it conducts electricity, allowing the charged powder to be drawn to the part thus completing the circuit. That leaves out all other non conductive items, can they be powder coated too? Hot flocking is the most common way of powder coating non conductive objects by heating them up to temperature, pulling them out of the oven and then applying the powder without needing to connect the grounding cable or plug in the gun. The part is already hot so the powder melts on contact. Once there is full coverage you put it back into the oven to finish curing. This method is proven and utilized by many manufacturing companies but there are some other little known tricks to coat materials like glass without having to heat them up before. The Eastwood Dual Voltage Powder Gun is great because it has two power settings, a great feature when powder coating different thicknesses of powder and when applying multiple coats.
Check out the Eastwood Powder Coating page, you’ll find all the products and information needed to start powder coating in your very own garage.
First I wanted to set a baseline to compare to by powder coating a glass jar the traditional way by hot flocking it. I washed down the jar with PRE Painting Prep to remove any contaminants that might have been on the glass.
Next I taped off the rim and opening of the jar with Fiberglass Masking Tape then heated it to 400ºF. Fiberglass masking tape is used here because it can withstand the temperatures needed when powder coating. Under no circumstance should you use regular painting tape, it is not designed to handle high temps and the adhesive will melt off right away.
Once up to temperature I carefully pulled the jar out of the oven, making sure to not touch the outside of the jar. I then applied the powder quickly around the outside before the jar had a chance to cool down too much. When hot flocking it is not necessary to attach the ground or even plug in the powder gun, the powder will melt on contact causing it to stick to the glass.
If done correctly this method will allow you to achieve full coverage without any type of distortion. The only downfall with this method is how fast the jar will cool once you pull it out of the oven. To get full even coverage you must coat the part quickly, if you take too long it will cool off before full coverage is achieved.
The next method involves the use of aluminum foil to line the inside of the jar. From here you attach the grounding cable to the tin foil, “tricking” the powder to attract through the glass to the foil. Searching the web you will find others that have used this method each having differing results.
Even with the foil packed into the jar, it was still not enough to evenly line the inside of the jar. This caused the powder to unevenly attract to the jar, resulting in a somewhat blotchy effect on the glass. This look may be desirable to some but it will be near impossible to get full coverage with this method.
As you will see in the above picture, the aluminum did not cover enough of the inside of the jar causing there to be light and blotchy spots where little to no powder was present. Different amounts of foil and application methods may yield different results, these are the results I experienced.
The next method is very similar in theory but instead of using aluminum foil which may not conduct electricity very well, I decided to pack the jar with copper pot scoring pads. These can be picked up at you local dollar store in packs of 2-3, making it a very cheap alternitive. Copper is known to be a ver good conductor of electricity and with all of the small strands that make up the scoring pads it may work much better than the thin aluminum foil. The other difference between the foil test is the amount of material that was inside of the jar.
I was able to fit 7 pads on the inside of the jar by forcing them in and putting the lid back on. This ensured that there was even an even distribution throughout the inside of the jar.
The only problem with both of these methods is the actual thickness of the glass itself and the power rating of the powder gun. In some areas the powder attracted right to the glass in others it seemed as though it was repelled, this was very interesting because there was a fairly even distribution of copper within the jar.
At first glance the jar looks like it has full coverage with the copper scorers still inside, but after they were removed it had a different appearance. There two specific areas of the jar where the powder was unable to attract to. This may have resulted from the way the pads were packed into the jar
As you can see the coverage on this jar is much better than the jar with aluminum foil. More than likely the aluminum was not the best conductor and was not enough to allow the charged powder to attract. Since the copper was packed into jar and the lid was reinstalled there was much better surface contact throughout the inside of the jar.
After all three jars were done and set side by side, the differences between them were clear. Depending on the look you are going for the first two might be a great fit for you, but if full coverage is the goal hot flocking is the best method. When powder coating non metallic materials there are other methods than the traditional way of hot flocking the part. When coating glass it is possible to trick the powder to think it is attracting directly to the metal on the inside but there is no guarantee that you will achieve the same results every time.
Check out the Eastwood Blog and How-To Center for more How-To’s, Tips and Tricks to help you with all your automotive projects. If you have a recommendation for future articles or have a project you want explained don’t hesitate to leave a comment.
– James R/EW