I've recently bought some vintage lace hankies which were very pretty, but needed reviving, and at 5p each I thought they were worth a punt trying to get whiter again. Can't believe the trouble I had trying to find some Glo-white or something similar. A really nice young woman in the haberdashery section of a store confided in me that she used of all things ...... Steradent
to keep her delicate unmentionables white
. That was much easier to find, so I dissolved a tablet in some warm water. Wasn't too sure about the blue flecks, but that seemed preferable to the ones with pink flecks. I dutifully read the instructions - to immerse for 10 mins. or whatever (the hankies, not my gnashers) and forgot all about them. A couple of hours later in a blind panic I remembered. The water was a frightening blue colour - so were the hankies.
Fortunately, the blueness rinsed out - and the hankies? Very much revived and looking a whole lot whiter.
p.s. Lots more tablets left and works out a lot cheaper too. I just hate asking for the stuff though
I'm going to try it out on glass next.