I am making some large drawings on rives bfk that involve joining multiple sheets flush against each other. I got some "permanent" book binding tape to use on the back, to bridge the two sheets, but found that the adhesion of the tape didnt go deep enough into the paper, and after of couple of weeks being on the wall the paper would come off the tape, and the tape would no longer be sticky, but instead full of paper fibers that had pulled away from the sheet.
im wondering what would be the best option to permanently make these two sheets into one sheet. some kind of wet set glue, or a wheat paste with another kind of paper on the back? or just a different kind of tape?
any advice would be much appreciated.
-CJ

From your description it sounds like you are trying to duplex two sheets in order to create one thicker & heavier sheet to work on. For this project you will need a strong archival adhesive due to the size of the sheets you would like to duplex. The Framing industry does this often by dry mounting or cold mounting prints onto an archival board backing.

Our advise is first to do some trial and error using liquid adhesives commonly used for cold mounting. We recommend using the Krylon Spray Adhesive which is strong, permanent, and with an extended open tack time giving you some wiggle room to adjust your substrates accordingly. This spray is also PH neutral, archival and will not lead to yellowing.

One other option that you may want to consider is Lineco's Neutral PH Adhesive. This acid-free adhesive has excellent lay-flat properties and dries clear. This comes in a traditional glue format rather than a spray like the Krylon.

As mentioned before it is best to test these products before adhering your artwork.