Why Partial Drums Pile Up in Aluminum and Steel Coil Coating

    Posted by Sarah Ledford

    Jun 25, 2015 10:40:00 AM

    aluminum coating steel coil coating

    Are you dealing with partial drums piling up? Are you running out of space for them? Are you concerned about the money that is tied up in all this leftover paint? These partial paint drums could be costing you money in your aluminum coating and steel coating processes.

    Have you considered the reason you are seeing these partial drums? As it turns out, it’s fill volume.

    What is fill volume?

    Fill volume is paint left over after a run has been completed. Most of this is due to the paint in the pan. There will also be leftover paint in the hoses and pump (or pumps) in the delivery system. If a pan requires 15 gallons to apply paint to a coil and another two gallons to fill the hoses and pump(s), there may be upwards of 17 gallons left over after the run is complete.

    These remaining gallons end up back in the drum – and back in the warehouse – possibly never to be used again! Because pan-feed coil coaters may require 10 to 20 gallons of paint to operate, it is not uncommon to over-estimate the paint volume required to run the job. When a coater buys more paint than necessary to run the job, it means there will be more paint left over after the run is complete.

    Custom Colors

    Custom colors are a huge contributor to the partial drum problem. This is because custom colors only run once or maybe twice. Custom colors also tend to be quite expensive. The total system fill volume left over after the run is completed creates a new partial drum. These partial drums can represent a significant dollar value.

    For example, 10 gallons of paint costing $200 dollars a gallon will equal $2,000 dollars. This expense can add up quickly over several different custom colors! Coil coaters think that this paint can be kept as an asset. However, this paint can become degraded before it can be used for another job. So, in essence, these partial drums are not valuable; they are useless.

    Common Colors

    You might think that custom colors would be the only contributor to the partial drum problem. However, common colors such as white, beige, and black can also be a contributor during industrial coating or other coil coating runs! These colors tend to run more often and the next run can be started with the leftover paint from the last run. But, if the time between runs is too long, the paint may be too degraded to use in the next run.

    This is especially true if the leftover volume is fairly small and a lot of air is trapped in the partially full drum. Skinning over, drum rust, and cleaning rag or sponge remnants all contribute to degradation of the partial drum.


    Contamination is another common issue that impacts partial drums. If the same paint is used often for custom colors or common colors, contamination in the paint can build up over multiple runs to render a partial drum unusable.

    Also, drums that run in the winter months may have excess solvent added to thin down the paint. This mixture of paint and solvent may be too thin to run in the summer months, when the paint may need to be thicker to run in warmer weather. This can lead to the drum being discarded and money lost.

    Reduce Pan Volume

    In an attempt to reduce the partial drum problem, it is common practice to make changes to reduce the pan volume. Most coil coaters have tried engineering custom shapes and dimensions to minimize paint volume. The goal is to use less paint in the pan to run a job.

    However, reducing pan volume does not address pump and hose volumes required for machine operation. As stated earlier, it may require several gallons of paint in the hoses and pump(s) to operate the coater. This amount of paint is necessary regardless of the amount in the pan.

    If not carefully controlled, however, this effort can lead to a whole host of issues. Some of which include decreased finish quality and inconsistent film build in the form of diminished edge-to-edge and head-to-tail film consistency.


    In short, your fill volume has a huge impact on the number of partial drums you have to deal with. And I don’t need to tell you that these partial drums not only waste valuable space, but also consume cash, not only in paint cost, but also in hazardous waste disposal costs. And all of these are very important overhead concerns for coil coaters.


    Download the free Cost Reduction Calculator to see where you can cut your overhead without cutting quality.New Call-to-action


    Topics: coil coating, paint and coating, coating aluminum

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