Lith question

[12pmc]

Any comments - I have been experimenting with Lith printing, and tried using Ilford FB Warm Tone paper (Lith dev Fotospeed A&B mixed as per instructions - 20°C). The image appeared after 20 minutes with constant moving of the tray. But the result was blotchy with cobweb (white lines) like pattern over the entire print. I then tried some old stock of Forte Polywarmtone and the result was fine.

Is the Ilford paper not suitable to Lith or is there something I should be doing or not doing.

Thanks
Peter