How does tubular glue "age"?

[Gsinill]

I just removed old tubulars, supposedly installed over 10 years ago but given how dry the tires were, it looked more like 20:


Tires came off really easy, leaving whitish kind of gooey glue
5 min. after soaking the rims with Goo Gone, all the glue wiped right off

With all the other rims I cleaned lately, it took a Goo Gone bath overnight.

Now, given the previous owner of the bike, I am pretty sure he did things right, so I am wondering whether this is normal for old glue.
I actually would have expected it to dry out rather than turning gooey and losing its adhesiveness.
Or did tubular glue just get so much better/more durable over the years?

[shovelhd]

It depends what kind of glue. 3M HiTack gasses off and dries up to worthlessness. Red Tubasti is like iron and tends to last a very long time. The question is how has the base tape aged? Cotton dries out and falls apart.

[Joxster]

After five or six years, maybe reglue them ;)

[DerekB]

I bought a used set of Zipp 303's that had whitish residue between the rim and tire. I rode them a few times and then replaced the tires. They may have been 5 years old. Similar sticky white goo on the rim. I'm convinced they were glued on with the wrong kind of glue, not proper (Vittoria Mastik is the only one for me!) tubular rim cement.

[Gsinill]

After five or six years, maybe reglue them ;)

For now they will only server for stretching.
Was just curious whether this kind of "aging" is normal for glue, didn't look right.

[11.4]

Mastic One -- just to stick to the most popular brand, no pun intended -- does show its age on a rim.

The purpose of a rim cement is to hold the tire onto the rim, obviously, but it also has to allow the tire to lift off the rim bed surface and after returning, to re-adhere. Anyone who's used old track shellac knows what the alternative is like -- it finally fractures or peels and then you have zero adhesion. The problem with re-adhesion for a tubular is that after doing this numerous times, the mating surfaces undergo a structural response and some of the colloidal contents in the cement start to crystallize. That yields the white powder you find in old glue jobs. It sometimes doesn't take a lot of riding to start it, in particular if the rim cement is old when applied and if it's been exposed to excessive heat or has any degree of separation of the colloidal contents from the solution they basically float in. Water exposure also will accelerate this problem, as will dirt contamination, which is why cross tubulars that are well used one season should ideally be re-glued for the next. I frankly prefer to re-glue all tubulars once a year simply so I know that the quality glue joint is in place. It's a good check on things during the winter, and if done carefully doesn't damage the tire or the rim. If you get to where you have that white powder in your glue joint, the constituents of the rim cement have gone bad and then you really should clean the rim completely and dump the tubular, because they can contaminate any new glue you apply.

To the OP, the reason your rim cleaned up quickly is because the rim cement basically crystallized and most of it simply lifted off without having to be dissolved. When it's gooey, that's just because the crystals are hygroscopic and tend to acquire water, but the crystals are now a separated colloid partially dissolved in water, which is scarcely an effective adhesive any longer.