Solvents for cleaning soap film?

[DaveE]

I have a DIY project question.

Background:
I was caulking a tile to tub gap in my bathroom remodel with a silicon based caulk (Mapei Mapesil T Plus). Caulk was applied then sprayed with a dilute dish soap and water mix for tooling. But I had some cosmetic issues so I wiped out about half of the caulk and then let it dry for 3 days (so far). Now I want to recaulk it but I'm sure there's a soap film that I want to remove so the caulk will bond well.

Comment:
Unfortunately much of the web thinks a "soap film" is about hard water with old mineral deposits, which this isn't. It's just Dove brand dishwashing liquid.

Question:
Is there a better common cleaning solvent than water for soap? Paint Thinner? Acetone? HCl?

 

[.Scott]

Use warm water, then wait for it to dry. If you don't want to wait, use a hair dryer.

Soap is very soluble in water. And the water will readily evaporate leaving nothing behind that will interfere with caulking.

Also:
anything that the shower is made from will be water tolerant.
in the manner you will be using it, water is non-toxic

 

[BillTre]

Any adhering soap molecules might be resolublize-able with a pH change. I have used weak acids for this (in lab, weak HCL, but at home maybe vinegar). This has worked for me with tissue culture equipment which is a very sensitive use.

 

[symbolipoint]

I may be misunderstanding the practicalities of this situation, but a solution of alcohol & water could help rinse away detergent solutions and their foam very well.

 

[DaveE]

weak HCL

Like 5% perhaps?

 

[BillTre]

Like 5% perhaps?

Even less would be what we did. But we were removing any left over lab detergent from the wash cycle.
5% would probably be fine.

 

[Borek]

5% HCl is 1.4 M, that's already quite concentrated in the context of just changing pH (yields pH in the zero range, that's seriously acidic). I would start around 1% (which is probably an overkill as well).

 

[.Scott]

According to Google AI:

You generally should not apply new silicone over old silicone for a long-lasting, watertight seal because oils migrate out, preventing proper adhesion, but you can do it if the old bead is very fresh (hours old) or if you use special products like a silicone restorer or a compatible primer after thorough cleaning, though removing the old bead is always the best and most reliable method for a durable finish.

I searched on "silicone over silicone".
In addition to the "oils" described above, I would be concerned about the ability of the new silicone to extend existing chains below the old surface. If a thin (say 8mm) sheet of silicone was formed from a first pouring followed hours later with an adjacent (as opposed to layered) second pouring, I predict that the preferred tear path would be along the boundary between the pourings.