Thank you so much for the insight it helps

Anything BUT wood is the more stable choice. And heavier, and full of more "real wood" particulates.

Just for clarity… MDF and HDF are not really more stable than wood, they are more uniform than wood. Solid wood is very stable longitudinal with the grain but moves a decent amount tangential to the grain. Particleboards are just wood particles instead of wood fibers and they don’t have any direction so they swell and shrink uniformly. Veneer core plywood is more stable than MDF or HDF.

Every benefit to particleboards are also their weakness. Because there are no fibers, there is no tear-out, so it is easy to tool. It is also easy to paint, etc. However, because there are no fibers it isn’t nearly as strong, and has little impact resistance.

Let’s take this to cabinet doors. You don’t want painted full MDF doors. Even small bumps with pans and utensils can damage the doors. So, we generally like to see MDF or plywood panels with wooden rails and stiles. Where the wood rails and stiles meet the MDF panel you may get small cracks in the paint (the rails and stiles may only move a tiny amount but they still move), this is usually minimized by that being an edge already.

Also acceptable is MDF wrapped in a decent thermofoil. HDF is just higher pressure MDF, it has more impact resistance because it is denser, but it still doesn’t match the fibers in wood.

I hope this helps.

Your environment should influence your decision. In the two parts of the country where I have been (Hawaii and North Carolina) the high humidity makes MDF less desirable.

I’m in CA

I'm sorry Lomo but my contractor in Hawaii and my cabinet maker in North Carolina would not agree with you. I wish I still had the trim we replaced that had swelled to 120% of its original size. The DIY project done by the previous owner closing in a front lanai was completely replaced this year due to the MDF degrading.

Let's talk specifically about shaker cabinets. There is no time where standard MDF is a stronger/better product for shaker cabinets than veneer core plywood. MDF is more "stable" than wood, but less stable than plywood, so the big advantage that most people believe that MDF has, it just doesn't. Plywood is much more impact resistant, has more strength, and cabinet grade plywood typically uses marine glues and so they have great moisture resistance.

Plywood is not suitable for raised panel doors because the edges are not suitable for finishing. This is why people started singing the praises of MDF's stability, because there was no other suitable "stable" product. However, shaker cabinets don't use raised panel doors.

I am not advocating for plywood. MDF has one other big advantage... it is significantly cheaper. Just because plywood is better doesn't mean you should pay extra for plywood. For most people MDF cabinet boxes and MDF door panels will exceed the life of the kitchen they are installed in. Paying extra for quality you don't need is just wasting money and statistically speaking you don't need the extra quality as long as you are using soft close hinges and drawer glides (which are a must for MDF cabinet boxes).

I wouldn't accept painted MDF rails and stiles. Impact resistance is important there and you are never going to get that out of MDF alone. Full MDF doors are a trend right now and I understand why. I could load up a full sheet of MDF on my CNC router and go to bed, come back the next day and have a dozen doors practically ready for paint. I am not a fan of the tradeoff... cope and stick doors don't take that long to make.

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Moisture resistant MDF (MR MDF) does OK in higher humidity environments, but standard MDF degrades significantly faster in higher humidity environments. This is a fairly standard research test and you can look up the results, which are pretty consistently a significant reduction in the modulus of rupture. Essentially, the glue holding the board together weakens faster because the wood particles are swelling more.

Having said that, MDF certainly doesn't have the same movement problems that solid wood does with high humidity swings. So you will not get the paint cracks as the wood expands and contracts, it just starts crumbling faster.

MDF all the way.

@bry911 you have provided a lot of great information in this post. If you were choosing between plywood and MDF on a shaker cabinet for yourself, which would you pick and why? Not an MDF cabinet box, just the center panel on the shaker door/drawers.

I wouldn‘t pay extra for plywood panels. If they were giving them away, then sure.

I would consider plywood panels a slight upgrade, but my experience says it is a profit center for cabinetmakers so they typically have more than a slight upcharge.