I can't do rayographs per say since the paper is already exposed to a nice deep black...
But I did do a second try this afternoon but this time using an inkjet print that I waxed with paraffin (tea light candle and blow dryer).
This is a 10 minute print, but this time I printed the image as a negative and had the wisdom of adding a printed step wedge to the print.
Now, this gave me a really surprising result. After 50% density, everything is faded to black. So I have less than half the usual contrast range to work with.
It also allowed me to make a special contrast curve to adjust before printing.
When I adjusted the levels to get a decent looking scan, this is what happened: living psychedelia!