Why doesn't she just roll out some foil or wax paper or the like? Something disposable.

I couldn't tell if the OP is talking about putting the placemats up there for out-of-the-way storage of the placemats? Or to put them there just to collect any grime up there.

How on earth would putting placemats on top of the cabinets void the warranty?

If it's to collect grime, then wax paper is much better. If she is "calling a couple of cabinet companies" because she is considering cabinets for a kitchen renovation, then she should use the reno as an opportunity to take the cabinets up to the ceiling and not have the issue of grime up there at all, plus extra storage for things like holiday items, candles, and the like.

Sometimes it's better not to ask the company.

Personally, I think the plastic placemats are better because you can keep reusing the same ones instead of throwing everything out every time.

However, I don't understand how this is supposed to work. Is she planning have naked cabinets with no trim that stop well below her ceiling? If she plans to have any kind of molding, it's going to be a chore trying to get anything over that to clean/remove.

It won't damage anything. Are her cabinets actually still under warranty?

Yes, agree Writersblock about the molding - that is why wax paper is better; it fits up there very nicely, and won't be visible. Plus the "throwing out every time" is really not bad, because you only have to do it twice a year at the most, and even once a year would likely be enough.

What about oilcloth that's cut to fit?

I certainly agree with Fori.

I run a length of paper towels on top of my upper cabinets. They're the perfect width, very inexpensive. Periodically wad them up and throw away, add new ones.

Agree....something you can wad up and throw away instead of having to clean and stir up the dust while cleaning (bad for those of us with allergies to dust!)

Another option....newspapers.

I'd use something recyclable.

Why on earth would placemats void a warranty? I may be missing something big, but I can't get my mind around this idea.

I have a loooooong run of cabinets in my classroom -- probably 18' of upper cabinetry -- that doesn't reach the ceiling. I ABSOLUTELY HATE IT because my students throw garbage up there, and I can't see it.

At the end of every school year, I climb up there and lay down a layer of newspaper ... it works, and it's free.

Everyone....I didn't understand how it would void the warranty, either. I was hoping someone here would shed some light on that. I think companies just tell you that. I love everyone's idea about using something that you can just throw away. I will pass that along to her. And I think I will try that on top of my cabinets. Sure would beat having to take the plastic placemats and washing them. To those who said you never have to clean if there is molding up there....the molding I have seen in other homes does not go all the way to the ceiling. There is still a space. I would think it would still get dirty up there.

Something similar: When we bought our mattress a couple years ago, we read the small print, and it says that if the mattress is stained the warranty is invalid. How does that make any sense?

The only way I can see that it might void a warranty is that the plastic would possibly have a bad effect on the finish over time (might leave marks), but who's going to be looking at the finish on the cabinet tops?

Yes, it does get dirty up there. Probably. Nobody would know if nobody looked. It's okay to be dirty up there.

I solve this issue by not having open space above the cabinets. It started as a lazy way of dealing with hanging perfectly level cabinets against a ceiling that was probably unlevel, and it became a fashion.

You guys are so smart! I love the idea of paper towel, wax paper or newspaper up there to just throw away! I had white cabinets with crown and dust was terrible to clean :( now that I'm doing dark cabinets does anyone have a great idea for me to use up there? Mine aren't flush with ceiling b'cause of vault ceiling and some can be seen from the loft area...any ideas what I could use? The good thing now is that I'm not doing crown so it will make it so much easier but wondered if there was something I could just lay up there for easy cleaning?

If they can be seen from above, then you can't put stuff up there unless it looks nice. A nice decorative piece of fabric, machine washable? Like a piano scarf.