A very common question that we get asked is whether you should use pumice stones (aka lava stones), gravel or sand in the bottom of a clay chiminea.
So for those new to chimineas you need to add a layer of insulating material in the belly of your traditional clay chiminea (there are modern clay chimalin chimineas that don’t require this – I’ll mentioned those at the end of the post) to protect it from the intense heat produced at the base of the fire. Without this layer your clay chiminea will almost certainly crack upon lighting of the first fire.
Our advice is to put the insulating material in up to with a couple of inches of the mouth of the chiminea.
The most typical materials that are used are sand, gravel and pumice stones (which are also commonly called lava stones).
Let’s go through the pros and cons of each in turn:
Sand is the cheapest option and is a very effective insulator against heat. So far so good. However, the main drawbacks with sand are that it holds moisture (which is not great for clay chimineas as it can lead to the clay becoming damp) and also because it is next to impossible to clean when you have a build up of ashes from each fire.
Sand is also dense and heavy. This makes it more difficult to get a fire started and adds a lot of extra weight to your chiminea.
Like sand, gravel is also cheaper but perhaps not as readily available. It is better in terms of holding moisture than sand but will present similar issues to sand when it comes to starting a fire. It is a little easier to clean.
3. Pumice stones aka Lava stones
Simply put pumice stones / lave stones (they are the same thing) are the best solution for your traditional clay chiminea. They are lightweight, very easy to clean and do not hold nearly as much moisture as sand or gravel.
Lava stones is a natural insulation material (it is used in lots of other fields including construction etc) and it also diffuses heat. And you’ll also find it easier to get a fire started than with sand or gravel.
Hopefully, that’ll give you the information you need to decide for yourself what material you’d like to try in your clay chiminea.
Now for those who don’t want to deal with the hassle of lining the base of the chiminea (or even curing it) then you should take a look at the ‘Chimalin’ range of clay chimineas. These offer the best of clay chimineas with the convenience of a clay material that doesn’t crack. You can find more about chimalin chimineas on the Chiminea Shop website.