Anyone who has placed a hot teapot directly on a wooden table knows about the damage it will cause. Sometimes that white telltale ring will fade with time, but more often than not it will always be there. I've tried using denatured alcohol to remove and it usually does at least an okay job, but it always damages the finish a bit.  We own a historical bed and breakfast inn with lots of antiques, so I can tell you first-hand that it's a lot safer to invest in a trivet. They are not expensive and they will save you a lot of time and worry.

Our cast iron trivets are made to be used with our cast iron tetsubin teapots, but they can also serve double duty and be used for any teapot or hot serving plate or pan.