1. what is the difference between ILFORD Multigrade IV and Multigrade Classic?
2. some papers have a grades like grade 2, 3, and 4, for example grade 2 papers it will gives a print a tone of filter #2 without put the filter or no?
2. some papers have a grades like grade 2, 3, and 4, for example grade 2 papers it will gives a print a tone of filter #2 without put the filter or no?
If you have grade number on paper (2, 3, 4) - then you don't use filters with this papers. They are fixed grade papers. Filters are used for papers that have variable grades (multigrade, polycontrast...), and with different filter you decide which contrast you want.
Usually when printing fixed grade 2 paper - it has harder contrast than multigrade paper with filter 2 (maybe it is just me).
MG Classic is the new and improved version of MGIV. Go here for the product data sheet and such. What looks promising to me is the nice smooth contrast curves. No little jogs that multi-grade products have had in the past. There are a few threads that discuss the product at length if you search.
Personally, I am looking forward to finishing out my current larder to change to the new products.