Thinning CA with Acetone

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Suborbital Maniac

Well-Known Member
Jan 22, 2014
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My water thin CA is suddenly no longer water thin; it's more like medium.

Since I don't use it for structural applications, I'm thinking of thinning it with some acetone.

Thoughts ?
I think it's no longer thin, ironically, because of the water that's leached in from the air. I think acetone will dilute it, but in no way will it restore it.
Regardless how it is stored. CA has a shelf life. yes cooler is better, but buy fresh CA. If you do not use throw away.. Bob Smith CA's are the best and I am sure they can advise. Give them a call.. You know beef in the freezer will not keep forever.
Man, I gotta wonder if adding acetone to CA might make for some VERY nasty poisonous fumes.

Even if it didn't "seem too bad" at the time (longer term lung issues).

CA is cheap, your long-term health ain't.
Probably no particularly problematic fumes, beyond the acetone and CA themselves. CA once polymerized will be dissolved by acetone, but I believe that's a one way reaction and the dissolved CA can't re-polymerize.
I wouldn't say CA is "cheap" at $7 for the smallest bottle, but I hear you.

My thought was that it has absorbed moisture and acetone was clearly not going to desiccate it.

My understanding is that keeping unopened CA in the fridge will extend its shelf life but doesn't help any once its been opened.
I wouldn't say CA is "cheap" at $7 for the smallest bottle, but I hear you.

$3.99 for 1/2 ounce bottles at Hobbytown and others who carry BSI (which is a great reliable brand).

Unless you want/need the "odorless" foam safe "gold" formulation, which is about $8 for 1/2 oz.

The other thing is that to me when CA gets too old, it loses a lot of bond strength. The models I build usually count on having normal strength, weak or brittle joints not worth using "glue gone bad", even if technically it would cure and hold parts together. Though on occasion there's some project where a crapload of "gone bad" glue does not matter for the quality, like applying CA as a surface finish or just to harden balsa parts,

Otherwise, sort of like having old milk way past its "best buy" date, smelly and lumpy. Would you give that to your kids or get some new milk for them?
It is never too old until it sets up enough you can't get it out of the bottle. There are lots of uses for old, partially set up CA. Hardening the inside of LPR tubing, balsa nose cones, paper shrouds and witch's hats on the TLP kits. Take yer old CA to the launch and use it to fix the scout's broken rockets. Some old, thick CA is easy to apply in the field, then just a spray on accelerator and even bad breaks are fixed in a jiff.
I have definitely had some thin CA on occasion that was OLD, which did not want to cure easily, still "watery" (not thickened), and was brittle/weak.