Question on What is the White Stuff

The "White Stuff" is High Density Foam.
My Father "Sam" used foam underlay on his layout. It is very easy to use and not that costly, So I have done the same thing with the Main South Line layout.
The foam comes from Solartex Sales@solartex.com.au Sheets are 8' by 2' , but for transport they are cut down to 4' by 2' sheets. I cut them in to 1 & 1/2 " strips and sand the top two edges a little to remove the square corner look and make it easier to Ballast. I normal order 10 sheets at a time. Well back to work.