This is taken from Getting To Zero Waste by Paul Palmer.
If you have spent much time using paint you may have learned a few things about how the process gets into trouble if you don’t use up a whole can at a time:
- Paint cans rust around the top. They also rust around the bottom if they have any exposure to moisture. Then the bottoms can fall out when they are lifted.
- If you are a bit lazy about closing the tops perfectly (which is easy to do) the paint will dry out inside. After a few openings and closings, the cover no longer fits right.
- Paint forms a tough skin across the top. The skin is removable but small pieces may remain in the paint requiring filtering. It wastes a lot of paint in forming the skin.
- With time, the paint no longer dries as well as it used to and may even remain permanently sticky.
- A paint can can be knocked over, creating a mess.
- A paint can hides the paint that is inside, requiring that the can be opened to inspect the paint, including viewing the color, and requiring that you carefully reseal the cover, which bends the metal a bit more each time.
- Paint pigments settle to the bottom of the paint with time making the paint unusable without a lot of special mixing.
- Pouring paint out of a can leaves the groove around the cover full of paint, making future closing difficult
What seems clear is the the problem lies largely with the kind of packaging used. Steel cans are a wonderful invention. They are strong, cheap, rugged and available in the millions. But they are as compatible with paint as kangaroo legs on a fish.
The problem from the paint’s point of view consists of air exposure. Especially the oxygen. Oxygen attacks paint, causing drying in the sense of forming a skin. This can’t be helped, since paint is made to dry and form a skin after it is applied. The air lets the solvent (including water) evaporate.
So how can we preserve the FUNCTION of a paint can with a better designed package. We need one that is easily accessed, that delivers its paint reliably, that shows the paint inside, that excludes air AND can easily be refilled.
Fortunately, these requirements, while uniquely aggregated in paint, have been partially dealt with in other systems. Wine also is destroyed by oxygen and intravenous fluids can be contaminated by introduced air. The package that solves problems for these products is a flexible plastic bag with an easily accessed delivery spout.
For use in paint, we need to do more than just change a package. We also need to change the filling, delivery and usage systems that go with it.
A flexible, transparent bag works best when it can be suspended high like on the hooks we see in hospitals for intravenous administration. A bag of paint could be suspended and delivered in small batches into a dish for brushing. Or, even better, it could deliver its product directly into a spray mechanism without the need for a pump to suck it up (like out of a can). A delivery tube to bring the paint to a spray gun would become part of the flexible system and could have its own closure at the gun so that the tube would not have to be cleaned out between applications. Delivery pressure can be created by a mechanism that carefully squeezes the flexible bag.
The bag has many advantages:
- The paint color and condition is easily seen.
- Mixing paint can be done by massaging the bag.
- As the paint is used, the bag collapses, always excluding air so that the solvent doesn’t dry out.
- Since oxygen is excluded, no skin forms.
- Because the bag has a compact, carefully designed closure at the bottom, it can be attached to a filling mechanism for the same paint and refilled from a bulk container.
- Once the filling mechanism is designed and debugged, a customer can go down a series of bulk containers, attach his bag correctly and do the filling himself. This could be part of a refilling station design (see that project).
- Numerous bags can all be hung up in a row (in a paintshop or a garage), making it easy to select the desired color for touchup.
- Because the bags collapse, there is no need for separate containers for pints, quarts and gallons. One size can be filled with as much paint as a customer needs.
- Because the bags are easily refilled, there is no need to sell bulk paint in very heavy and cumbersome five gallon lots as is done currently. One or two gallon packages would be sufficient.
- When a package is refilled many times, it is worthwhile to invest resources in making it strong, robust and carefully designed. The bags can be heavy duty and the closures do not need to be cheap, light and disposable as so many are today.
- Bags can have some solvent or water introduced, shaken around and cleaned out for use with a new color or kind of paint if desired. The progress of the cleaning will be easily to monitor through the transparent bag.
- The bag may be punctured. Since the bags will be refillable, they can be made very rugged and they can be stored inside of cardboard (or even steel!) boxes.
- Paint may dry out around the closure. While it may be enough to peel dried paint off the non-adherent plastic surfaces, design of the closure with a sturdy cover will be a major thrust of the design requirements.
These are some of the obvious benefits of a new way of designing paint containers. More will probably emerge as the new designs are tried out and debugged.
Today, there are recycling projects which consist almost entirely of collection of cans, with little reuse possible because the paint is in doubtful condition and the containers unreliable. Since the new design will maintain paint in far better condition, with no paint running down over the labels, and the bags will have a high intrinsic value, actual reuse of paint, rather than discard will become commonplace. One can imagine racks of used paint bags hanging up for new users to select from.