I had to move much of the film archive to a garage after I suffered a flood in June. I had a few reels on the concrete floor. When I picked them off the ground, I saw one with vinegar syndrome left a ghost image on the concrete floor. The metal reel looked fine. Storage time on concrete was about June 28, 2026 to August 11, 2026. The white part is where the film was on the reel. The metal has no image on the concrete. Can't say if it is due to VS or not, just reporting what happened. Film was reel #1 of #2, of a Hitler documentary probably by Leni Riefenstahl. (I didn't watch it, just going by label.) Did the ghost of Hitler do it? That is what the superstitious would say, huh.

Anyone have an idea how V.S. affects concrete or some other explanation for the ghost image?

Google:

Vinegar syndrome is caused by the chemical breakdown (deacetylation) of cellulose acetate plastic used in old photographic films, magnetic tapes, and LCD polarizers. As the plastic ages, it reacts with moisture and releases acetic acid—which creates the sharp smell of vinegar and triggers a self-accelerating cycle of decay. [1, 2, 3, 4]

DDTJRAC said:

Vinegar syndrome is caused by the chemical breakdown (deacetylation) of cellulose acetate plastic used in old photographic films, magnetic tapes, and LCD polarizers. As the plastic ages, it reacts with moisture and releases acetic acid—which creates the sharp smell of vinegar and triggers a self-accelerating cycle of decay.

What is the self-accelerating decay time line? Hours, days, years before the film is unusable?

What you see is typical for concrete. The white stuff is efflorescence, the deposition of salts onto the surface, either by evaporation of water that has moved through the concrete and carried salts along, or by reaction of the concrete with an acid, producing the salt and pitting the surface.

The white deposit is for the most part calcium (bi)carbonate if the water migration has leached some calcium from the concrete itself, or some other salt if reaction with an acid.

Different acid reactions with concrete will produce different salts -
- acetic acid ( vinegar ) --> calcium acetate
- muriatic acid ( HCl ) --> calcium chloride
- carbonic acid ( CO2 + water ) --> calcium carbonate

Not to scale, guestimation:
If the film was giving off 10 μg of acetic acid per hour for 40-ish days, the reaction of the acid with the concrete would deposit around 10g of salt. <-- not chemically balanced for scientific purposes

Knowing the amount of deposit would give you some indication of the present rate of decomposition of the film, assuming that an analysis of the salt deposit rules out any other chemical reaction other than acetic acid and concrete.

It is kind of difficult to high five on what the white stiff really is unless one can go and poke it with a stick.

One reservation I do have is that the concrete looks to have surface that has been sealed. Any direct reaction of acetic acid and concrete would then have been hampered, and to what degree is up for investigation.
Perhaps it is a deposit from reaction with surface dust.