IMRON..............IS AUTOMOTIVE ACRYLIC ENAMEL from DUPONT. as i said i SPRAY PAINT MDO with automotive paint. it is this kinda paint. as for expense, its not more expensive.No matter what you do to MDO, it seems the top layer will bubble up, it just absorbs the moisture like a sponge.
Although there was a sign company back in Cincy that use to use Imron, we never tried it, its pretty expensive
We would brush an elastomeric compound on the edges, and paint with 3 coats of enamel (no primer) the theory is that
the enamel would soak into the MDO and bite, really did not work very well.
We actually use MDO for Landuse signs here, and discovered that Rust-Oleum Professional works well for background paint (less expensive than 1-Shot)
BTW, MDO was never meant for the sign industry, but the manufacturers were more than willing to sell it to anyone
it was designed for the concrete industry, for foundation walls etc.
Some old timers discovered it, and started using it in the 60's I believe.
Have fun learning the trade!!!
If correct, I believe MDO and its far superior brother HDO were developed to be used in building the PT boats made famous by JFK and of course McHale's Navy. The HDO version is harder to get, but has marine grade glues and a much harder surface. I remember versions in the 90's being riddled with "boats" and lots of edge voids, but like most anything its all about the raw materials. Most MDO comes out of the Pacific Northwest and frankly, the veneer stock is not nearly as clean as it used to be because frankly, the big old growth forests are gone.
I've been schlepping it, cursing it, futzing with it, etc. since 1980 and this much I know. Give me a piece of pan formed aluminum with 1-2" returns on it any day if its a simple rectangle shape the client orders. I rarely use 3/4" anymore because its too heavy and costs as much alternatives that give the same thickness but are much lighter to carry around.
I've tried a variety of edge treatments and have found a very watery TiteBond2 slather along the edge prior to priming with any good quality primer to be very durable. Can't really say water-based or oil, I've had great results with both.
I always ease my edges ever so slightly and ALWAYS at least prime the back with a neutral color. In fact, unless the background color is white, I always tint my primer. There was a time when simple Chromatic or Ronan bulletin colors covered almost as well as 1Shot, but those days are long gone.
All this being said, unless it is a permanent landmark sign, we shouldn't be promising or expecting extraordinary durability. Especially in these climate change affected times, with higher UV exposure no matter where you live.
Tell a realtor their simple For Sale 4x8 will last 15 years and they'll be bringing it back in after every sale for you to recycle it. With each install it will more and more pitted with holes, dents, scratches, etc. for you to work around.