Singapore 1980 Ships 1c Varieties

I am working on a custom album page for some Singapore Ship varieties. These are not listed in Scott (do not have a post-1970 SG) but listed in Std Catalog of Malaysia Singapore & Brunei.

My question is about the 1c variety. It is not listed a fluorescent but I have 2 different versions. Both versions look dull from front under UV but the rear of one is very reactive under UV. If the said 1c to 75c was fluorescent then I would take the note that ordinary paper is not reactive. It could just be a catalog error.

I remember the 80s when these stamps were regularly used on envelopes.

Angore, as I recall there is more than one type of phosphor for the 1c. I thought there was a printing with a phosphor band, but I have to dig out one of my well-hidden older Gibbons to confirm this.

I'll try to look it up today.

My Stanley Gibbons Brunei, Malaysia, and Singapore Catalog 4th edition 2013, lists only ordinary paper for the 1c stamp.