Feathering Cement on Amiga MDF Enclosure?

[TheManFromDenver]

Any experience and recommendations with coating an MDF cabinet with feathering cement as a finish? It’s typically applied in a very thin layer and is strong on floors and walls in a room. But wondering if the vibrations of the speaker cabinet might be too much for this type of coating.

I am considering this for the Amiga cabinets, so the walls will have some lower frequency vibrations.

[fpitas]

I'd worry about putting something water based on MDF. the stuff gets swollen; but maybe it's ok. If it's wall damping you're looking for, a thin layer won't do much. You're a lot better off adding some simple internal braces to combat wall flex. Not that I think the Amigas need that, but it's kind of fun.

[djg]

Try it on some scrap, especially "end grain".

[TheManFromDenver]

Perhaps the MDF could be primed with something to block the moisture content of the cement slurry. As long as the cement wouldn’t eventually be cracked and bounced off the cabinets over short time.

Motivation is really aesthetic. Have a cement accent wall going up and it would be neat to have the speakers conform with a color tint for contrast.

[Operandi]

I'd worry about putting something water based on MDF. the stuff gets swollen; but maybe it's ok. If it's wall damping you're looking for, a thin layer won't do much. You're a lot better off adding some simple internal braces to combat wall flex. Not that I think the Amigas need that, but it's kind of fun.

Sounds like the idea behind it is for the aesthetics. I think it would be pretty unique looking and would look good with a tall slender speaker like the Amiga.

It should be possible to seal the MDF to keep it from absorbing water which I agree you'd want to prevent as I'm sure you'd want the MDF to be as stable as possible for the concrete. Not sure what would be best to use though.

[fpitas]

Yeah sealing is a good plan, as long as the cement will stick to the sealed surface. Maybe polyurethane?

[a4eaudio]

I would think a few extra coats of primer (Zinsser 1-2-3 and Zinsser shellac based are popular on MDF) would work.

[Operandi]

Would that be enough of a moister barrier though?

I was thinking coat the entire thing in epoxy and let it cure.

[a4eaudio]

I don't "know" for sure, but I'd think 3 or 4 coats of the shellac primer would be. It's not like it's being soaked in water with the concrete mix. People use 50/50 wood glue/water mix to seal the MDF edges and it's not like it swells up and deforms. On the other hand, I have MDF baseboards that have gotten soaked and swelled up and pretty much fell apart.

[davidroberts]

I have had my best results dealing MDF with boiled linseed oil. I never use a water based product on MDF for the same reasons mentioned above. Fiberglass resin also works very well but is quite a bit more expensive and a PIA for sealing.

[TheManFromDenver]

Those are good suggestions for protecting the integrity of the MDF. Regarding the cement, I have to imagine that someone has done this before to know whether the cement coating can maintain its integrity against the vibrations of the cab.

[squib]

You can also try emailing the concrete maker to see if they have any guidance. Shellac is a good suggestion, but you'll definitely need multiple coats. Alcohol based BIN dries very quickly.

Low viscosity epoxy resin would probably be better. Its not cheap.

[djg]

The Ardex brand video I watched shows it being applied over wood. I don't think you'll see any significant vibration from a 3/4" MDF speaker cabinet.

[Chris Roemer]

It seems to me that your biggest challenge will be avoiding "bumps" along an edge. Outside corners in a home often show the plaster "scars" from accidents.