I don’t have a real answer for you but I will say that olive oil works well for this.

I worked on a Christmas tree lot through my winters as an undergrad and olive oil always worked well. Of course then you need soap and water to remove the olive oil.

Coffee grounds or that mechanic paste might do pretty well also

Haven't heard of walnut grounds, and yes fast orange is meh. Thanks for the suggestion.

This is great for when the contaminant is oil soluble but not water soluble.

Guessing inside (white side) of orange peel will work too (the oils are used to make various cleaning products).

IIRC This is why "goo gone" product is really good with many adhesives.

That's my favorite adhesive remover. And it cleans up well afterwards with Dawn soap and water.

Does it have a generic name for non-American audience?

I don't know if it does. It's the original from here: https://googone.com/original

I imagine there are variations in other places, I think it's mostly concentated citrus oils from oranges.

Coconut Oil works as well.

Also works for jackfruit residue.

I would guess that since pine sap (and any other adhesive) sticks, it does not allow for soap molecules to surround it.

If you, like me, often find yourself covered in pine sap. The product: Shout, for removing laundry stains will make quick work of removing sap from skin. Maybe the answer to your chemistry question is in there.

I looked up some SDS sheets, and it looks like there are multiple formulations with completely different ingredients.

Isopropyl alcohol works well for cleaning pine sap.

Something to do with the difference between solvents & surfactants I imagine.

Pine sap are not water soluble, even with soap. Pine sap is resin based, resins need a different solvent that can dissolve it such as alcohol or mineral spirits. It the same for wax (THC/CBD) resins, they need alcohol to clean it off.

It the same for blood stains on clothing. They are not generally water soluble, you could get them out if you put it under cold water if the stain is still fresh. Hydrogen Peroxide can dissolve blood stains (fresh or old) since it can be used as a solvent.

I'm pretty sure with H2O2 (hydrogen peroxide) it's actually destroying the chromophores in blood (among other things), not dissolving stuff.

Put differently, it breaks up the stain molecules into smaller molecules and causes other reactions that change them, it doesn't just dissolve them. You can dissolve resinous stuff with various solvents, you're right about that. Stays mostly the same, just goes into solution.

If you use Hydrogen Peroxide, it will often also take some pigment with it from the clothing if that’s what your are getting the blood out from. So be careful not to inadvertently bleach something.

It does just not very well. Maybe the pine sap is more interested in being stuck to pine sap than soap?

There are things that are much better at cleaning non polar molecules off of surfaces, alcohols, gasoline, lye, brake cleaner etc, but they’re not great at cleaning your hands because they strip the lipids that make up your skin off.

Ironically I've found that lotion is better at cleaning resins/flux off my hands than soap alone.

Maybe for the same reason that you can remove greasy hair pomade (or other hard-to-wash-out hair products) from your hair by first applying a conditioner, then washing with shampoo. Supposedly the fats/oils in the conditioner bind to the grease and lets the soap get both.