This morning I thought I'd test out the Lush bubble bar as I am not in work till later. I watched a YouTube video last night on how to cut Lush products. I chopped my bar into 4 and popped a quarter into the bath. Here are the effects. Although it doesn't shimmer as much as the whole bar would, it did produce a lot of bubbles. I thought I would be covered in glitter as your hands get covered in glitter when chopping it but that didn't seem to be a problem.
I would use this product again, but I am not sure if I would spend the £3.65 again. I would love to try this in a hotel bath with the jets as I went on holiday to New York and ran my dad a bath so he could soak his ankle. I popped a tiny bit of shower gel in the bath and it turned into mount Kilimanjaro. I'll see if I can find a photo.