How to clean powder coating plugs
Various means for extending the life of masking caps & plugs
We get these questions a lot from customers: “How do I clean the powder off silicone plugs and caps?” or “What is the best way to clean masking caps & plugs?”
The unsatisfying answer is: It depends. But! You have options.
Let’s look at each one. It will be important for you to test if any of these are best for your operations, and if the time, labor and money spent for equipment and/or chemicals is worth it compared to simply replacing the plugs.
Chemical Stripping of caps and plugs
This is the option customers ask about the most. Viadon knows of at least two chemicals that customers have used in their process successfully. Whether they will work in yours will require you to test it with the powder(s) you use and see if it works and is cost effective.
- AquaStrip ACB by Hubbard Hall.
- SC200 by Spartan Chemical (one customer indicated a 50/50 dilution with water and stripping them overnight).
Advantages: Generally removes most or all powder. Time required can be short – as little as several hours, but may require overnight or 24 hours
Disadvantages: Possibility of caps & plugs being altered in size due to swelling or shrinking, time required may be lengthy, may require supervision by employes, protective measures often required for employees (gloves, eye protection, other PPE), and possible contamination of other washing / coating processes if all the chemical is not removed before using caps plugs again.
Viadon generally does not recommend using chemical stripping of caps and plugs due to the numerous disadvantages.
Also, certain chemicals are not recommended for stripping caps and plugs at all, such as MEK, acetone or mineral spirits.
Tumbling / Vibratory Stripping of caps and plugs
This method can produce adequate results but also requires some additional steps to avoid contamination later. Caps and plugs (sorted by size or color, generally being ideal) are placed in a tumbler or vibratory equipment to mechanically remove excess powder from caps and plugs. The nature of the process means that there will be small bits of powder left over, often clinging to caps and plugs even if it is no longer cured to the masks.
This means an additional step of washing and rinsing the caps and plugs in a mild detergent (either sprayed in a mesh bag or in a bath with some agitation) to remove any excess small bits of removed powder to avoid downstream contamination is necessary.
Advantages: Once sorted and equipment is secured, generally simple to do by placing caps & plugs in equipment and turning on the tumbler. Does not require supervision by employees. Typically maintains cap / plug size integrity.
Disadvantages: Requires careful sorting, almost always needs additional step of washing parts in a mild detergent and perhaps rinsing, and generally does not remove all powder. Can degrade some caps or plugs dimensional accuracy over time or if too aggressive a process is used.
Manually remove powder from caps and plugs by hand
At least one of our customers has tried both the methods above over the years and concluded that manual removal of powder by hand is the ideal method for them. Their take on it is that sometimes other aspects of business are slow, so when employees have less work to do, they can work on removing powder from plugs by hand during those hours. If the plug has become compromised (soft, split, broken, etc.) it is thrown out. If powder can be taken off easily by rubbing it with the fingers, it is removed and the plug returned to production or perhaps sent to a wash station to remove possible contaminants like finger oils or bits of powder.
Advantages: Makes good use of slower times during the day for employees. No harsh chemicals or PPE to worry about. Employees can inspect plugs while cleaning them.
Disadvantages: If work is busy, plugs may not always get cleaned when needed. Not all powder will get removed. Contaminants can remain if plugs are not washed, so an additional step to wash masks may be necessary. Generally is labor intensive.
Throw out plugs with built up caps and plugs
The last option is also a valid method: Toss the plugs or caps in the trash when too much powder builds up. At some point through repeated oven cycles, silicone degrades over time. And when enough powder builds up, masking lines no longer look clean on metal parts.
For smaller plugs and caps, it may not even be worth the time or money spent on any of the above methods, so throwing the plugs away when powder begins to build and affect masking may be the most cost-effective option. For larger or more expensive custom plugs, a cost/benefit analysis may be useful to determine the best course of action, whether that be cleaning or discarding and purchasing new ones.
Advantages: The only labor required is to sort good/bad parts. No chemicals, PPE or equipment required.
Disadvantages: May have a higher cost, depending on the size and expense of the plugs or caps.
In conclusion, there are multiple methods to strip cured powder coating from silicone masking caps and plugs. What is right for your operation will depend on multiple factors. These include your goals, equipment, available labor, calculating / balancing costs of masking parts along with labor to clean caps and plugs and the need for precision in masking as parts either get build up or degrade over time.
Viadon carries a wide range of stock powder coating masking caps and plugs that can be found here.
Custom caps and plugs can also be designed for your specific needs, often with low cost tooling and short lead times. And if you ever have any questions, we always pick up our phone during work hours and answer most emails in 60 minutes or less.
Looking for a masking supplier that is “A cut above?” Viadon has you covered.