Because most cotton fiber papers are not adequately sized (with gesso-like sealants) they are considerably more porous. I would strongly suggest that before you do any oil application on Coventry Rag or any other paper substrate that you do a small test on a sample sheet.
My experience has shown me that any oil resin medium is likely to bleed through to the reverse side of the sheet. Just like painters still gesso a less absorbent substrate like canvas to ensure good surface hold out without bleed through without question any paper should be surface treated with a gesso like product. Hence by coating the sheet you want the oils to sit up on the surface and dry by oxidation.
If you don’t have a sample of the Coventry Rag we would be more than happy to send you a few samples - my suggestion would be to try the 320gsm Vellum.
My experience has shown me that any oil resin medium is likely to bleed through to the reverse side of the sheet. Just like painters still gesso a less absorbent substrate like canvas to ensure good surface hold out without bleed through without question any paper should be surface treated with a gesso like product. Hence by coating the sheet you want the oils to sit up on the surface and dry by oxidation.
If you don’t have a sample of the Coventry Rag we would be more than happy to send you a few samples - my suggestion would be to try the 320gsm Vellum.