1928 $1 Silver Certificate, Special Paper

Can you notice the difference in paper/finish?

I guess we can say the testing was inconclusive

Basically a typical government fiasco. Put large red s and r on notes and people will think they are special and pull from circulation so little info to gather from this "experiment". Nonetheless, the notes are collectible.

True for collectors but most people ignore the SN & details in their cash (other than the marker for denomination).

I had a rare treat in speaking with a Bank of Canada employee who happened to know a great deal about the history of our banknotes. We talked mostly about "insert replacements" because he was most amused by collectors' who desired to save them. By that time our Journey 'inserts' were merely odd prefixes discovered in bricks (usually with different prefixes & then identified) by other collectors who then fed that data to Charlton & other sources. The same practice occurs with the BOE in the UK.

He said that most of decisions made at BOC (& our 2 printers) were made from economical perspectives (eg: to decrease the costs of printing special 'X' designated replacement batches) & they would never consider a collector's mindset. [So it was our printers who would have suggested getting rid of the designated replacement- not the other way around). I found this employee quite amusing as he always spoke to me like I was a reporter with such qualifiers as "off the record" or "you never heard that from me" (& I suppose management enforced a strict confidentiality work ethic there).

The majority of test notes produced in Canada had innocuous (SR, GR, ER & RS) prefixes so were only later discovered/identified as such by collectors. The BOC employee stated that all test notes were generally field testing cheaper paper/inks in how the note faired from general circulation. I would suspect that the OP's 1928 & 1935 notes mentioned were employed for the same purposes. While some of the production runs were minor here (like our rarer old * replacements) the majority of test notes were printed in the millions but since collectors seldom successfully identified them (early to save them in high grade) few in high grades exist (& book values have remained high).

Nice find! Experimental issues are kinda neat to find and can easily be cherry-picked. Here's my 1935 C-B block exp.

I understand it to mean the status quo. No changes.

Yes. They are still within part of the experiment, even though they weren't changed. Third party grading with usually give them their friedberg number followed by exp. They do pretty well at big auctions, especially in high grade.