Surface Treatment for Valchromat Workbench Top

[Mike Kreinhop]

I'm building this large MFT-like workbench using locally available aluminum extrusion for the frame. The workbench is 1x2 meters and has a 19mm thick black Valchromat for the top instead of MDF. This is still a work in progress, but I would like to treat the surface with something like polyurethane to make it more durable.

Does anyone here have experience with Valchromat and can offer suggestions?

[Jim Becker]

A google search provided this explanation from Atlantic Plywood for what this product is:

https://www.atlanticplywood.com/brand/valchromat/

Base on that, I suspect you can use any kind of finish you want, although the resin used to make it, since it's mildly moisture resistance, may not take a penetrating finish as well as "regular" MDF. I have put oil on Extiera and it appeared to soak in a little, but it was not ideal. For my auxiliary bench, I used some left-over oil based polyurethane, but the caveat there is that it scratches almost immediately as you begin to use it. My suggestion to you is to test some oil or similar on some scrap of that material and see if it soaks in a little. If so, that's the way I'd go for sure.

BTW, that work table looks great!

[Mike Kreinhop]

Thanks, Jim! I have a few offcuts to experiment with different finishes.

I based my workbench on the "BF/MFT Workbench" by Ryan at The Garage Journal (aka AtomicRyan on FOG). Ryan used a full 4x8 sheet of MDF for his workbench, and applied 15 coats of a 50/50 mix of wipe-on polyurethane and mineral spirits. My shop will not accommodate a workbench that large, so I reduced the size to something I can work with.

[Mike Kreinhop]

I went to four hardware stores trying to find matte finish hard wax oil, but the best I could find was semi-matte. The 250ml can in the image below is more than enough for three coats on my workbench top.

I made a test run with an offcut that I used for testing the Parf Guide kit and the Forstner cutter. This piece is divided into three sections, with a shallow saw kerf dividing the sections, and each section prepared with different sanding. The saw kerf dividing the upper and middle section is not visible in this image, but it is there. The top section of three dog holes and the Forstner hole is unsanded. The middle section of four dog holes is sanded with P150. The bottom section of three dog holes is sanded with P150, P220, and P400.

I applied a think coat of the hard wax oil and made sure the chamfered edges of the dog holes were coated. After ten minutes, I wiped off the excess and let it dry overnight. This morning, the surface was dry and I could not see any residue when I wiped it with a clean cloth. All of the dog holes were clear, and I had no problem with the dog binding in them. I applied a second thin coat and wiped off the excess after ten minutes. The image below is what it looked like about four hours after the second coat. I don't think I will bother with a third coat.

I'm very happy with the results so far, but will let the test board set for a few days before deciding on the sanding finish. I'm leaning towards the P400 finish, but I could definitely tell the difference between the P400, P150, and unsanded surfaces after the first coat.

[Jim Becker]

That looks great and really brings the black color forward. I'd also do the sanding up to 400...it's not like it's going to take a long time, honestly.