I am going to build a cabinet section with a roll-out portion to allow going behind for added storage. The roll-out section will be 24″ W x 14″ D x 48″ H and weigh about 250 lbs. total. The floor is epoxy-coated concrete. We have experienced a problem with rubber wheels on it; the rubber softens and sticks to the floor. Don’t know why. The roll-out portion will only be moved no more than a few times a year. My problem is what kind of material should the casters be made of to prevent flattening over time? Flattening would pose a problem moving it under load. Thanks for your help! – Gary Kueppers
Tim Inman: What kind of wheels? Get something hard, like a hard plastic or phenolic wheel. Why? The harder plastics will be less reactive. Materials like epoxy do not just “harden” and then stop. Even though it might look to us as though the reaction has finished by the next day, the material is continuing to react, and will continue to react for several weeks or even months. Among other things that are happening, the material may be “off-gassing” or releasing vapors which can be destructive to softer plastics which probably contain things like vinyls. Actually, the vinyls in your soft wheels can be off-gassing, too. The released vapors are solvent-like, as you know, and are destructive to materials around them. They’re melting.
This off-gassing problem is one we finishers know well. Lacquers especially, and varnishes to a certain extent, release their solvent vapors for quite a while after they seem “hard” or cured. The worst case for a finisher is to build a nice, deep finish on a tabletop, only to have the new owner put a cheap plastic/vinyl “doily” on it. The two will melt together within a few days. For that matter, any smelly plastic, like baby toys and beach balls, will weld into a nice new lacquer finish. They will weld into an older one, too. The “stinkier” the plastic (lots of off-gassing!), the worse they will be for a fine furniture finish.
As a side note, the Steinway Piano company has been in the news recently. I have a finishing schedule they use. It requires 17 weeks from start to completion of the finish. Why so long? They build in plenty of curing time between finish layer builds to allow for complete solvent evaporation and finish curing before they do the final rub-out. Every beginning finisher has experienced the heartache of rubbing out a new finish too soon. After a few days or weeks, what was once the most beautiful high gloss polished top becomes something else. As the finish continues to cure, the fine surface ages into something that looks terrible. Off-gassing….
Chris Marshall: Tim provides an excellent rationale for why your floor coating is likely melting your casters. But, there’s no way epoxy, or much else for that matter outside of a shop fire, will melt a steel wheel. So, another option would be metal casters. Their load rating will be overkill for the 250 lbs. they’ll be moving, but your bases would definitely be covered. For example, consider these steel wheels from Rockler (click here). At under $10 per caster, they won’t break the bank either.