Ossus Amplifiers - Step 3, preparing the cabinet for assembly

MDF appears to be highly compressed cardboard. Its like particle board but the particles are "micro-sized", hence Micro-Dense Fiber (MDF). This makes for heavy, solid, and very straight boards. On the downside the dust from cutting them to size is also micro-fine and was really getting to me. The smell and the dust are a drag too. I decided to coat the MDF for strength and to seal up the dust and smell. Conveniently I had some appropriate coatings on hand. Recently I had recoated my hardwood floors under my desk, where there is maximum wear and tear, with a nice Minwax poly urethane. About two weeks ago I was doing a different project involving flat black spray paint. I decided to test both, layering each on the other in the four possible combinations to see which I liked the best. I knew that eventually the cabinet needed to be black, but the question was, glossy or flat? An aesthetic choice, but worth a quick test.

It only took a few minutes to put down a few coats of each (MDF on the left, poplar on the right in the picture). Coating the pieces has sealed them up nicely. The MDF sucked up both the black spray paint and the poly urethane like a new dry sponge. I chose to put one coat of poly urethane on, then assemble the pieces, and after that to paint over with flat black. The interior paint will be exposed, but eventually the exterior of the cabinets will be covered with black tolex, and if that rips I don't want to expose a brown wood color. Another benefit to coating the boards is an increased water integrity and overall stability. It was a bit disconcerting to see how aggressively the poly urethane was drawn down into the fiber. In my head I could see water just destroying an uncoated board. The wood will either be finished with a flat black spray paint or covered with tolex so the urethane will be totally invisible when I'm done, but I'll know it's there just in case.
It only took about an hour to finish the job and put the pieces aside to dry. The dust and smell are gone, and I feel better about the wood. MDF is an odd material. Next up, start assembly of the cabinets.

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