Can flux go bad ?

[clueless]

I have a small can of paste-type flux (the no noclean type) I've been using for probably 2 years. I left it in a room that was warm during Summer. and turned rather sticky. It is rather hard to remove even after a good drop of isopropanol and scrubbing.
Can it go bad over time or under specific climate conditions?

I'm also curious for the noclean liquid flux. Can it also go bad over time? A seller on ebay has listed some noclean flux that seems to have expired over 2 years ago..

 

[speedyink]

It can go bad. If it's physical properties have changed it's probably no good. If you're really curious you can always try it on a test board, if it works like absolute ass then you can safely assume it's pooched. The fact it's sticky and doesn't clean well is a definitely a sign, though.

Dunno about the liquid stuff, never used it.

 

[Tokimemofan]

Simple Question Complex answer only way to know is to actually use some. Flux is usually made of rosin+solvent+additives. The part that often goes bad is the solvent, making it more difficult to apply and to char quicker. In a pinch I had to use some WWII era flux and that was still quite effective but other properties made it less than ideal. Sticky and difficult to clean probably means that the solvent has partially dried. I wouldn’t worry about it for most applications.

 

[Nully]

I mean honestly, just buy some new flux. Buy no-clean and this will totally eliminate your issue in the future. If anything I'd say the solvent has just evaporated or something, try adding 97% isopropyl to it if you truly can't afford new flux. You can get a liter on Amazon for $10 from MG Chemicals, been using that for close to a year and do a ton of soldering with it. I only use sticky flux (sometimes) for hot air work etc, overkill imo.

 

[speedyink]

I'd say it's well worth a new tube... flux sucks when it's smokes and doesn't want to clean off. I mean really, we're talking like 8 bucks? Maybe?

 

[Tokimemofan]

I mean honestly, just buy some new flux. Buy no-clean and this will totally eliminate your issue in the future. If anything I'd say the solvent has just evaporated or something, try adding 97% isopropyl to it if you truly can't afford new flux. You can get a liter on Amazon for $10 from MG Chemicals, been using that for close to a year and do a ton of soldering with it. I only use sticky flux (sometimes) for hot air work etc, overkill imo.

Btw the MG Chemicals 835 is what I use when replacing M92T36 chips on the switch. Good stuff for almost anything just preheat good to boil off the solvent if soldering anything prone to shifting like bgas or other surface mount stuff

 

[clueless]

I mean honestly, just buy some new flux. Buy no-clean and this will totally eliminate your issue in the future. If anything I'd say the solvent has just evaporated or something, try adding 97% isopropyl to it if you truly can't afford new flux. You can get a liter on Amazon for $10 from MG Chemicals, been using that for close to a year and do a ton of soldering with it. I only use sticky flux (sometimes) for hot air work etc, overkill imo.

Thanks for the input
It's not a financial issue this whole flux issue. I got this can for around 3 dollars, and did a proper job for roughly 2 years up to 3 months ago. It's rather odd that the solvent evaporated in 3 months under room temperature.
I want to get some noclean flux, but unfortunately I can't find any on local shops . Buying from a international shop is a little overkill due to shipping costs. I live in a country where international orders over 20 euros (including shipping) are going through customs. I hope there is a good source in Europe though as these are considered local and don't go through the same custom shenanigans ..