The dust I use I have only found for sale in one hi fi shop in the UK.
Its specially designed to reduce RFI emission and best used on top of amplifiers.
It was really tricky to apply and took me several attempts to get right. I found the best way was to remove the top and place selotape under all the air vents, then sprinkle the dust evenly over the top, The container has a herb style sprinkle top to ease application. then remove the selotape, this removes the dust over the air vents and allows correct airflow. replace top.
The shop owner said they had run out of the powdered hens teeth which they suggest you use on Magna Planar speakers.