[Soldering] Vintage Flux?

Other Hardware General Electronics
1

I've got this old flux i've been using, wonder if anyone can tell me about it.
Little back story: (Skip to the bottom for direct questions)

Quite a few years back I was given about a pound worth of recovered solder.
This was used solder that had been recovered from pcb tear downs, etc.

Being the type of person who does not like to waste things I started using it for projects.
Seeing as it was just clumps and chips of solder I often would use separate flux.
I'd used the liquid flux in the past and it worked but I ran out during a project.

I went looking in the garage and found a tin of "soldering paste" (no idea where it came from) so im thinking this must be flux.
but it's not liquid it's a thick gel like form, the tin looked very old (no upc) the inside "paste" looked quite old as well but it was still very moist and look like it had never been used, so I said what the heck let's try it.

It worked, I dunno how old the stuff is but it worked a treat, I like it much better then the liquid flux.
just a tiny dab will do the trick and this stuff stays where you put it.
I've been using it for the last few years and i've barely made a dent in the 2oz tin.

recently I was looking at soldering supplies and I thought, ya know I wonder if I can find a "new" source for this stuff, I came up absolutely empty on google, the closest I found was a few listings on ebay for "vintage" flux.

on the back it says it contains "zinc chloride", so im thinking.. maybe I can just find flux paste that has that in it..
Im fairly ignorant with flux, up till that bag of recovered solder I didn't even have a use for flux, the rosin core 40/60 usually did the trick.
So after a little searching it seems like there is a wide world of flux out there (again I plead ignorance)
and that Zinc chloride is considered a corrosive, because it's usually obtained with hydrochloric acid.

So flux with zinc chloride is usually seen in automotive body work, etc, not electronics.
but then I read on a few more sources that say some of the "mildly active" (common) electronic flux also contain small amounts of zinc chloride.
So there seems to be some overlap here, im unsure of the zinc chloride content in this flux, it could be mild or it could be large, I've no way to know since I can't find any info on this product.

The little guy on the tin I thought was working on electronics, but now im wondering if he's not actually soldering stain glass or plumbing or something.. or maybe the little guy on the front is a lie altogether lol.

I've been using it for the last couple years and thinking back I don't recall having any problems with things i've used it on, but most of them was hacked cables, wire, and terminals, not much PCB work.
Who knows how fast "corrosion" might take, it's hard to check prior work because most of it is under shrink tubing.

So my questions are:

  1. What can you tell me about this particular "paste"? Estimated age?, was it ever suitable for electronics
  2. Should I be worried about prior projects that I used this with?, and if so can anything be done now?
  3. Can you recommend a GOOD non corrosive (no clean up) "gel" type flux?

Since I think this product predates barcodes (omgz) Im hoping someone here might know what this is about.

2

You have been using acid flux, which will eat through your circuits over time if you fail to remove
all traces. This stuff is designed for plumber's soldering, not electronics where rosin flux is used.

3

Can you recommend a GOOD non corrosive (no clean up) "gel" type flux?

These days there is a balance between flux that works and flux that is safe, in terms of fumes. The better the flux the more dangerous it is.

This is also true about the flux you have been using, very good but very corrosive.

Here is a good selection:-

I have used this one in the past and it is not too bad:-

4

I've been using plain old, generic "no clean gel flux" from amazon, and it seems to work decently well, and you don't have to remove it (though I almost always do if I've had to hand apply flux - maybe I'm just using too much).

I would avoid acid flux for circuitry, as you rarely need such aggressive flux. Then again, since you're using chips of cruddy corroded recycled solder instead of nice clean new stuff, you might have more need for flux than the rest of us. Acid flux like you use is still available, but it's not marketed towards electronics use (in fact, jars of similar flux sold nowadays often say "not for electronics use").

I strongly suggest investing in a new roll of plain old rosin core leaded solder (unless the solder you're using is lead free, in which case get that) - I can't imagine trying to use raw solder (I've got bricks of recycled solder too - not sure how I got it), but I always use new.

5

The little guy on the tin I thought was working on electronics, but now im wondering if he's not actually soldering stain glass or plumbing or something.

It looks to me he is doing some tin plate work.

6

I've always read that you should NEVER use "acid flux" for electronics and this is the 1st time I've heard of anyone using it.

If you are not getting corrosion after a few days or a week, you are probably OK.

For my home projects I've always used regular-old rosin flux. It has to be cleaned/removed with solvent or alcohol, but it's not corrosive if you don't bother to clean it.

At work, we usually use a water soluble flux which is somewhat corrosive so it has to be cleaned. It seems to be a bit more effective than rosin flux. If it's not cleaned, the corrosion is pretty bad after a couple of days. It's also somewhat conductive and it can sometimes foul-up operation of a PC board if it's not removed.

We also use a "no clean" flux, which leaves a clear residue. But, "we" doesn't include me and I have very little experience with it.

If I were buying flux for home/hobby use, I'd get the water-soluble kind. But, I'm just using rosin-core solder with no additional flux. It doesn't seem to be used much in electronic production anymore, and I think that has to do with the hazardous chemicals used to clean/remove it.

It worked, I dunno how old the stuff is but it worked a treat, I like it much better then the liquid flux.
just a tiny dab will do the trick and this stuff stays where you put it.

The water soluble flux we use isn't much thicker than water. It flows and spreads around but it washes off easily. (We dry hand-soldered or hand-reworked boards with compressed air, but you can just let it air-dry.)

[u]Here[/u] is a no-clean "tacky" flux.

I've been using it for the last few years and i've barely made a dent in the 2oz tin....

...recently I was looking at soldering supplies and I thought, ya know I wonder if I can find a "new" source for this stuff...

So, I guess you'll never need a new source!

Any hardware store should have flux for soldering copper pipes. But, I wouldn't be that surprised if they've changed the formula.

Being the type of person who does not like to waste things I started using it for projects.
Seeing as it was just clumps and chips of solder...

You are wasting a lot of time. :wink: Maybe you can make some fishing weights, or some little weights for some other use...

Or, you can use it in a [u]solder pot[/u] for tinning wires.

It's up to you, but a roll of electronic solder basically a one-time buy and a one-time expense. Or, you can consider it an overhead expense. The amount of solder (and the related expense) used on one project is insignificant.

7

MarkT:
You have been using acid flux, which will eat through your circuits over time if you fail to remove
all traces. This stuff is designed for plumber's soldering, not electronics where rosin flux is used.

Ya that's the feeling I was getting after reading about zinc chloride, What's the time frame on that? are we talking decades or...?
I've got some work done with this stuff going back about 2 1/2 years no problem yet.

am I looking at failure in another year or so? or is this probably a 10-15 year problem?
I do realize there's a lot of variants but If you could just give me an idea as to when I should expect problems.

Grumpy_Mike:
These days there is a balance between flux that works and flux that is safe, in terms of fumes. The better the flux the more dangerous it is.

This is also true about the flux you have been using, very good but very corrosive.

Here is a good selection:-
http://uk.farnell.com/webapp/wcs/stores/servlet/Search?st=flux&catalogId=15001&categoryId=700000006498&langId=44&storeId=10151

Ya I'll have to get some new flux :confused:
To bad this stuff was ancient but awesome... although It sounds like it might haunt me in the future.

DrAzzy:
I've been using plain old, generic "no clean gel flux" from amazon, and it seems to work decently well, and you don't have to remove it (though I almost always do if I've had to hand apply flux - maybe I'm just using too much).

I would avoid acid flux for circuitry, as you rarely need such aggressive flux. Then again, since you're using chips of cruddy corroded recycled solder instead of nice clean new stuff, you might have more need for flux than the rest of us. Acid flux like you use is still available, but it's not marketed towards electronics use (in fact, jars of similar flux sold nowadays often say "not for electronics use").

I strongly suggest investing in a new roll of plain old rosin core leaded solder (unless the solder you're using is lead free, in which case get that) - I can't imagine trying to use raw solder (I've got bricks of recycled solder too - not sure how I got it), but I always use new.

I've still got a roll of radio shack rosin core, so I can use that in the mean time till I get some new flux.
I just using the recycled stuff cause it was free and Im all for recycle/reusing things when possible.

Actually I've not mind working with the recycling solder, only down side is it's in little's and not a spool, but most of the time that's not are a downside for me.
To be honest in some way's I've actually found it better then working with flux core solder because you have a lot more control (or at least I feel I do).

I had no idea till yesterday that there was more then 1 type of flux.. rosin, and that some of it was corrosive, I mean it's made to be used on metal :confused:

Have the convenience of flux cored solder just facilitated that ignorance, before using recycled solder I had no need for flux at all.

MarkT:
You have been using acid flux, which will eat through your circuits over time if you fail to remove
all traces. This stuff is designed for plumber's soldering, not electronics where rosin flux is used.

Question.. what do you mean by remove all trace?
Wouldn't it still be in the joint?

I use this stuff very sparingly. not because it's dangerous (which till yesterday I had no idea) but because it works so well you don't need a lot and it's a gel so it's not messy at all.

Many times I'd even apply it with a sewing needle.

DVDdoug:
I've always read that you should NEVER use "acid flux" for electronics and this is the 1st time I've heard of anyone using it.

If you are not getting corrosion after a few days or a week, you are probably OK.

~

At work, we usually use a water soluble flux which is somewhat corrosive so it has to be cleaned. It seems to be a bit more effective than rosin flux. If it's not cleaned, the corrosion is pretty bad after a couple of days. It's also somewhat conductive and it can sometimes foul-up operation of a PC board if it's not removed.

Ya I had no idea about difference flux's till yesterday, plead ignorance here.
I'll keep an eye out, just yesterday I did some work on a wireless router and my arduino so I'll keep an eye out.

DVDdoug:
The water soluble flux we use isn't much thicker than water. It flows and spreads around but it washes off easily. (We dry hand-soldered or hand-reworked boards with compressed air, but you can just let it air-dry.)

[u]Here[/u] is a no-clean "tacky" flux.

So, I guess you'll never need a new source!

Wonder if I can get that in a tin, I've found my self often applying the flux (since it's a gel) with a sewing needle just where I need it.

DVDdoug:
It's up to you, but a roll of electronic solder basically a one-time buy and a one-time expense. Or, you can consider it an overhead expense. The amount of solder (and the related expense) used on one project is insignificant.

Agreed, I've got some rosin core from radio shack, I was just using the recycled stuff because it was free and good for the environment, I've actually not had any real complaints about using the recovered soldier 99% of the time it works just as good as new.. infact somewhat better since I can control exactly how much flux I want to use.

Thanks for the reply everyone.
I was hoping someone would say, no joe it's all good, but I kinda had the feeling it wasn't after reading yesterday.

Oh well, learn something new.

8

When the "solder/copper" alloy step occurs while heating the joint, the flux will not remain inside the joint... it will, however, be all around it and this is what needs cleaning if it a more acidic flux. That little 'ring' of remaining flux can eat the copper right next to the joint.