Johnathan, melamine backer MDF is "quite" common among mat. distributors, ask your local supplier.
"great for CNC-ing, as "more precise" surface machining holding (less warping or say, bowing) when machining, regardless of hold downs, ( mechanic or vacuum, as I have, will not hold "properly" (say against bowing) as it as a difficult to hold cause by suction going through machined MDF !!
MY 2ct, ...
Ya, I'll second as for it's a common use to "cure" or say at least minimize this warping effect.
my "peev" with it, you still have to work "say a lot" to prep it since, over-spray from spraying sides will inevitable produce over-spray on this melamine backer.
Few solutions, sure ( Ie, tape & paper, ruff sand before and spay surface too....etc)....my point, it's extra cost (the material part + labor part) & extra time anyway....over 20yr in this trade, my take....much, much more efficiency by simply spray regular backer a few time before, as suggested in my previous post....
Again, in respect to any other opinion ( respectful or debatable!?!)....it's my way of doing a cheaper and yet, yield a best to better result "for me" !
All the best, good luck