If it's not Polygrade, it's Bromofort. Those were Forte's only cold tone offerings. Polygrade was certainly available as a fibre based paper and it was variable contrast. Bromofort was graded, and in my opinion much colder toned. Both lith, with very different results. I found the Bromofort to give a very pronounced bromide drag effect - a vignette if you will. Polygrade, does not show this effect. I've also found that Forte papers vary a great deal from batch to batch in lith. Dramatically. One box of Polygrade will lith wonderfully, the next will be a dull thud.
See this post I made in regards to printing with old, fogged Polygrade.