Question: I would be interested in your Rhino / Line-X polyurea cartridge dealer startup kit. I’ll check my compressor tonight to see the rating. It is a bigger compressor so I might be all right. What is the air dryer you mention, and do I need it?
Answer: Air dryers come in various forms. The most expensive are usually refrigerated dryers which don’t require desiccant replacement or reactivation. The most affordable are usually desiccant dryers which require you to replace, or sometimes to recharge (by drying in oven or such) the desiccant. You can see some examples at: https://www.grainger.com/category/pneumatics/compressed-air-treatment/desiccant-air-dryers . While any coating such as paint will have issues with a spurt of condensation, these coatings cure very rapidly, are thick, and are reactive to moisture until cured. If you get a spurt of moisture, or drip onto the surface and spray over it, the coating will blister. With a paint job, that just means a little bit of sanding and spraying over the spot, you would require more effort to remove, feather, and respray a bedliner product. Also, if you spray only a partial cartridge for spot repair, you will need to replace the mixing tube. The tube is only about $4, but would add to overall cost if you had the need to replace often.
Best recommendation is to also check with your local automotive finishes supplier. All paint shops of any reputation would be using a dryer for the air supply, so whatever they recommend (and probably sell) is worth considering.
Another thing…. You should be fully draining your air compressor either daily, or at least weekly. Not only does the condensation destroy your tank, but oils (if not oil free compressor) collect, and the excess moisture will require you to replace the desiccant very often. An air dryer which also includes a chamber to filter oils and contaminants will avoid a lot of situations where you need to repair spots in a bedliner. Most issues with polyurea bedliner jobs are caused by poor prep, or lack of attention to the application process itself.