Your old soap bar is worn down to a nub. What is the best way you

[raccoon]

Know of to get it to stick like glue to the new soap bar?

[JustAnotherGen]

1. Netting

My aunt boot used to tie them all (nubs) into netting

[MiHale]

2. Duct tape...

No seriously, we use Kirk’s Castile soap, when it gets small it goes into a wide mouth gallon container filled with water. It will dissolve down and we use the soapy water for an insect spray on our plants.

[lastlib]

3. Get LOTS of suds on the new bar, and press the old piece into the suds.

Put a weight on it while it dries.

[Easterncedar]

4. I don't. I put it in a liquid soap dispenser with a little water.

Waste not, want not.

[LoisB]

8. I do the same.

[eppur_se_muova]

5. Save up your scraps, then melt them all together. Several methods online.

https://lifehacker.com/how-to-turn-old-soap-slivers-into-new-bars-of-soap-1848461827

[ms liberty]

6. The trick is to use your nails to make crosshatch marks on one side of each bar

While each bar is only slightly damp. Press the two together, wiggle just a tad while pressing together and then carefully get the bar a bit more wet while turning it over in your hands to create lather. Fill those edges between the two bars with the thick lather, and I mean thick, really thick - then set the bar down and leave it to dry. I usually leave the small bar side up, and then I will be a bit more careful using the bar the next time or two, to make sure they continue to meld into one.
The real key is to create hatching or crosshatching on one side of each bar, and then making some 'slip' to fill in and join the two.
This whole method was adapted from what I learned in pottery class forty years ago, lol.

[keithbvadu2]

7. The soap bars are shrinking in size, so you get to the nub even faster nowadays.