Solder

[SilverSolder]

Sticking with the same type of solder for years "trains your brains" to know how it acts in a wide variety of situations - that saves a lot of time.

So, to a beginner, I'd say - choose a good brand/type, and stick with it for a long time - your skills/learning will become cumulative that way.

[tooki]

I wouldn't mix 44 and 245 on purpose but both are designed to be left on the board. 44 if left however shouldn't exceed 185C (probably will burn). Kester recommends cleaning both 44 and 245 with a saponifier (flux cleaner). You can get away with cleaning some rosin flux with IPA if you don't let it sit long, when it hardens it's more stubborn to remove. So individually mostly removal of those two flux is for cosmetic reasons.

Note that you cant just magically add a solvent and expect flux residue to evaporate, it has to be scrubbed rinsed or wiped off and rinsed etc.

Edit:

Now that I have said this, I see plenty of people use a no clean flux pen with rosin core solder. Do they have problems, probably not. I tell people though to start at what flux you want to use then buy the wire that has the same flux if possible.
It's best not to overthink unless you are willing to read up on all the different types of flux and applications, as the next person will say they use Kester 331 and your head will start hurting.

Despite Kester’s instructions, Kester 44 does clean fully with just IPA. However, I’ve yet to find a flux that isn’t removed with less effort using proper flux remover.

As far as being told to not mix fluxes: I think it’s more about process predictably than anything else. When looking at the ingredients of various fluxes, I noticed that there are plenty of fluxes on the market that contain the ingredients of both traditional rosin fluxes and modern rosin-free fluxes.

[tooki]

Piggybacking on OP, people here have an opinion on Kester 44? I figure more aggressive flux would be better for beginners.

https://www.kester.com/products/product/44-flux-cored-wire

Kester 44 is great — it’s what I have at home right now. With that said, someone here on the forums recommended trying Kester 245, which is no-clean, but whose flux apparently significantly outperforms 44. I’m gonna try it when my roll of 44 runs out.

44 sounds pointless if true. Is mixing flux bad? Cos I already purchased RA flux with the same classification as 44.

1. If an industrial or service process specifies a specific flux type, then that’s what will be used. I’m sure many, many processes still specify Kester 44.
2. Traditional rosin fluxes like 44 are generally easier to remove than no-clean fluxes, whose residue tends to be much more stubborn. (In most situations, neither rosin nor no-clean residue needs to be removed, but when it does, no-clean is much harder to get off. They generally do not clean thoroughly with just IPA, demanding the use of a commercial flux remover. Though I recommend that anyway, see my previous reply above.)

[Shock]

As far as being told to not mix fluxes: I think it’s more about process predictably than anything else. When looking at the ingredients of various fluxes, I noticed that there are plenty of fluxes on the market that contain the ingredients of both traditional rosin fluxes and modern rosin-free fluxes.

Easier to predict outcomes yes, it's why I suggest known branded rosin core lead or lead free with rosin flux, hard to go wrong from there. I would probably use Kester 44 myself but I have Multicore with Ersin 362 among others.

 

[DasDingleberg]

Do you recommend any particular flux remover?

[tooki]

Do you recommend any particular flux remover?

Every solvent-based flux remover I've used so far has worked well. Without comparing them side by side (since I haven't had them at the same time), I wouldn't say I've observed any huge differences between the ones I've used, but with the Electrolube product perhaps having a slight edge. (Or maybe I'm just imagining it, since I like its smell — it uses orange oils, and smells like it!)

I've used Electrolube lead-free flux remover, Kontakt PCC (aka Kontakt LR), Techspray, and Distrelec's house brand, which is almost certainly made by Electrolube, since they were both made in England.

All of them readily outperform simple IPA and/or ethanol, especially on no-clean flux, which leaves white residue when cleaned with just alcohol.

In a nutshell, I'd check your favorite distributor and buy whatever their cheapest solvent flux remover is.

I've also used Electrolube Safewash water-based (saponifying) flux remover. Worked great on rosin flux, but really struggled with no-clean. I think they make a newer formula that is more effective for that.