# Varying grades of MDF?



## PRGDesigns

Are there differing grades of MDF? I had some leftover MDF from a project several years back and it was significantly different than another piece of MDF from a different project. I don't recall where I purchased either piece from, since I moved a lot during the time period of those previous projects. One of the pieces appeared to have coarser particles in it and cut much smoother than the other piece. It was also significantly harder/denser than the other pieces and was more of a yellow color versus the pale brown of most of the MDF I am familiar with. Any help is always appreciated. Thanks in advance for any consideration you can give this matter.


----------



## MonteCristo

Not sure but I would say that there likely are. There certainly are different qualities of particle board and some of the really dense ones look a lot like MDF.


----------



## Loren

Yes, it varies. If you want the best stuff, go to a 
commercial plywood dealer.

People got freaky about the formaldehyde in 
and these days you can get it without. I think
Home Depot is selling the stuff now. There are
also various densities of MDF. It used to be all
real heavy (90 lbs per 3/4" 64 sq. ft) but it seems
like it doesn't always weigh so much these days.

I have bought "ultralight" MDF and don't recommend 
it for unsupported spans or even frameless carcase
parts.


----------



## Wdwerker

Oh yes! There are different grades. There is HDF high density fiberboard and lots of varying qualities in between. We sprayed some MDF scraps the other day to make some new faces for toekicks. Half of them turned out fine, but half of them took 3 or 4 more coats . They were less dense and the face would not smooth out. This is why I usually do not use MDF. But in this economy if the job calls for it, why argue?


----------



## harrymontana

absolutely , it differs on the glue and the substance. Some Chinese crap is known to warp and twist and glue is only good for a limited timeframe


----------



## bondogaposis

The stuff varies depending on who makes it, each plant has their own proprietary methods.


----------



## Dutchy

Maybe this will help you (MDF Wikipedia)


----------



## saucer

There is even a outdoor grade now..


----------



## JAAune

I'm using one of the outdoor grades now for cabinets that will have sinks installed. This particular product is called Extira and is favored by sign-makers since it's 100% waterproof. I've had a cutoff sitting in a container of water for several days and it's not affected at all.

I've used the ultra-light stuff mentioned by Loren and while it's a high quality product made to exacting specs, I don't care for it since it's very soft. It's susceptible to dents even after veneering. I can see it being useful for large panels that will be kept away from traffic but I'll not use it again for anything like a table top.


----------



## MrRon

I'm using one of the outdoor grades now for cabinets that will have sinks installed. This particular product is called Extira and is favored by sign-makers since it's 100% waterproof. I've had a cutoff sitting in a container of water for several days and it's not affected at all.

Are you referring to MDO, which is a plywood used by sign makers?


----------



## JAAune

No. This stuff is not MDO. It's MDF all the way through and can be carved to any depth without sacrificing the waterproof integrity.


----------



## renners

Quality varies depending on where you go. When it comes to 'standard' mdf, you get what you pay for. I don't mind paying a few extra euro for a sheet that will paint better than a real cheap one.
There are moisture resistant and flame retardent sheets, as well as deep routing grade which has a deeper higher density layer.


----------



## PRGDesigns

Per Loren's suggestion, I visited a commercial plywood dealer here in the DFW area, Central Hardwoods. They offer two qualities of MDF, a "double refined" premium Plum Creek MDF and a standard MDF. The "double refined" Plum Creek MDF is superior to any other MDF from HD or Lowes, even though HD and Lowes advertise their MDF as "premium". I have used the "premium" MDF from Lowes in the past because they are much closer than Central Hardwood, but I have now switched to strictly buying the "double refined" MDF from Central Hardwoods. My CNC bits, same type, same vendor, same batch, last 4 times longer in the "double refined" MDF as the "premium" MDF from Lowes. The dust is much finer and more consistent with the "double refined" MDF than the coarse and inconsistent dust from the "premium" MDF from Lowes. The "double refined" MDF also finishes better, has less tear out, and has a smoother factory finish. Thanks to everyone who commented.


----------



## Loco

You guys actually spend money on that crap ? LOL.


----------



## lateralus819

MDF is terrible. Extremely heavy (extira is ungodly heavy, try handling a 1" thick sheet 4×8).

At work we use MDF a LOT. As far as the extira, its okay, try soaking it in water then letting it dry out and repeat. It warps like crazy. Leaving it submerged is one thing. If it's out and exposed to the sun it changes shape quite easily.


----------



## JAAune

The job we're about to deliver next week called for a paint-grade waterproof base and toe kick. It also required 10 foot long pieces and we had to buy a 192"x48"x3/4" sheet to get that. Talk about heavy. We had three people just to get it off the truck.

I don't see warping being a problem where we're using the Extira. Cabinet boxes under sinks and toe kicks in basements are the applications where we've used that product.


----------

