Last year I managed to buy #4 pearsalls direct from them - checking their site recently they have very few gossamer shades for direct sale.
I have no idea where the #4 sits in historical terms or what the correct shade of any of them is historcially - I don't necessarily hold with there being a correct shade as such other than a particular shade/colour may work better on your river and a different one on another.
Having only seriously got into tying spiders last year I fell in love with using pearsalls and started using #3,#4,#5 as thread only bodies on my olive dries.
#4 body , Coq de Leon tail, CDC compadun pointing slightly over eye was a tremendous success and I mean tremendous, all thru april and may and early june.
Anyone know whether #4 is available anywhere as I wanna stock up on it.
A few experiments are underway for this season.
1. Utilitising pearsalls silk for touch dubbing. Take a lenght of pearsalls and run it thru velcroe a dozen or so times and attached to the velcroe will be some fantastic ultra fine dubbing. Fiddly, but the resultant dubbing is excellent and easily mixed by hand to give some very subtle shades.
2. Using 2 of #3,#4,#5 as bodies on dries, body tied similar to purple and orange of dark watchett.
3. Ribbing say a body of #3 with a well waxed length of #4.
Old story, falling in love with a particular material and experimenting