There are also different kinds of slate. Our slate is a deep, clear black slate and that is the kind we choose to use high-quality North American black slate for our products because we think it is the best. Besides our type of slate, there are also light grays, dark grays, even greens, purples and reds that come from Vermont and the Northeast. Additionally, there are also different types and colors of slate from different parts of the world. The other 'black slates' you see on the market are from China or Spain and unfortunately are thin and brittle.
As you see from above, there are many types of slate on the market and no, not all slate is food-safe. In fact, some slate is very porous and can actually trap food and bacteria. Even the best slates for use in food settings (like ours) require some form of sealing.
Our slate is sealed using a food safe mineral oil and as long as they are washed and kept clean, yes they are food safe. Like any plate used for serving food, no slate is food-safe if it is not properly cleaned between uses.
This is a hard question to answer. Slate is very, very strong. Our slate especially. That is why we can cut it so thin and it will not break easily. A normal slate can handle having dozens of times it own weight on top of it.
The easiest way to think of natural slate like ours is that is is very similar to porcelain or glass. It is very hard and durable but it is likely to break if it is hit sharply by something hard or dropped on a hard surface. If you treat your slate like you would any dish or glass from your kitchen, your slate will be perfectly fine!
Slate is very close to flat, but it is not perfectly flat, no. That is why we use clear acrylic feet to level it which makes it flat for use. Many other slates on the market use cork feet or felt bottoms which do look nice, but if you glue felt to the bottom of a non-level slate... well it is still going to be a non-level slate, just with a felt bottom. Additionally, cork and felt are not waterproof like our slate.