Hi, On 17/03/2015 17:21, Tim Eck wrote: > I know dry sand is transparent to microwave but wouldn't damp earth shield > against radio frequencies? Doh... What is the deepest growing bulb. It's almost worth buying the kit to find out how deep it will go. The context was chipping labels or pots. But more power, more sensitivity. There is ground penetrating radar. -- David Pilling http://www.davidpilling.com/