:: anyone tried pure ROSIN flux?

[3roomlab]

i thought i share this pic. a small tin of pure ROSIN flux. the brown spot is where i dipped in the tip a few times, it kind of "charred". the "gummy" thing solidifies very fast. unlike the "chemical" based fluxes i have used, this thing seem resistant to "boiling" when a tip is dipped in.
tried a few wires and perf board, the residue looks exactly like those old PCB boards hand soldered, thick brown goo. being thick and gummy, when bits are applied to soldering surface, it does not "speed" off from the solder spot, but rather clump around the soldering blob, i think this is in work wise the better quality over synthetic flux which is comparatively really watery and runny.

and it smells fabulous, like somewhat a light incense, almost like a perfumed twig or something "green" 

i dont have any litmus, i doubt it would show since it doesnt have water content, not sure what is the actual pH. online info states it has pH around 4-5, is it really that high for natural rosins?

[Balaur]

Solid rosin was a "staple food" for most of my soldering life. Especially when I was younger, as consumables were hard to get by and much more expensive than just dipping your 100W soldering gun tip in the ever-lasting rosin jar.

And yes, it gets darker and darker as the years pass.
I've also used to dilute it with medicinal rubbing alcohol-like stuff to get some kind of coating liquid to protect my boards.

I still have a few matchbox-sized bricks of rosin laying around.
I'm currently using rosin-based liquid flux which is the same stuff really.

[3roomlab]

using rosin to coat PCB? pre-soldering treatment?

[Balaur]

using rosin to coat PCB? pre-soldering treatment?

Yes, both pre- and post-.

It worked very well on veroboards and it also helped when making your own PCB:

Scrub the oxidized PCB you got from you know where till clean; hand trace the PCB with diluted tar; etch the board; remove tar with gasoline, drill, protect everything with the diluted rosin; solder as needed; re-apply the rosin with a brush.

[3roomlab]

but it seems natural rosin is acidic, wont post treating be bad? or there is another purpose? or there is a neutral rosin pH 7?

[Balaur]

but it seems natural rosin is acidic, wont post treating be bad? or there is another purpose? or there is a neutral rosin pH 7?

Never seen any issue long term. 

After some googling around, it looks like the abietic acid - the main (80%) component of some types of rosin "does not attack the
copper metal under any condition": here

[3roomlab]

hmmm i didnt know much about abietic acid. thats good info ... more ROSIN then 

[radix]

Rosin is quite commonly used as a flux around here. AFAIK it's also in the cores of many different solders. It's usually disolved in alcohol or acetone and then applied to the PCB. I used it just the other day to solder a TQFP. It works reasonably well. It is also then painted over the exposed copper (homemade PCBs) to prevent oxidation. One reason that it is so popular here is that you can get it by the kg as it is used for pig scalding.

[atferrari]

Still have around a "stone" of it, inherited from my brother maybe more than 40 years ago when he still assembled TV sets at home. (Can't believe they were selling so well at that time). Licenced by US or plain copycat?

Diluted in alcohol, applied on a clean PCB served well as protection and for easy soldering.

Just last year I started to use flux which is definitely more practical except when tining stuborn cable terminasl which I dip in a molten very small bit of rosing immediately followed by solder.

What I could not know why, sometimes, the solution, long time after being applied (days) to the PCB is still too sticky. 

[3roomlab]

it is naturally sticky. its a purified tree sap / gum organic thingy. im just glad i got it now after using so much watery synthetic fluxes. so far in today's short works, the rosin flux no longer "paints" my iron tip black even at low temperature. but the fumes although lesser, seems more pronounced in agitating breathing. so it is likely i will dial a lower temperature to try. i did not dilute the solid "cake" with alcohol, have no alcohol (or beer) here atm ha !

[wraper]

LOL, I really don't get why you are so exited about it. It's the second worst type flux (in a form of the solid brick) after crappiest Chinese pastes. It's OK if inside of the solder wire but be excited about dipping your solder iron and burning it before it even reaches the solder joint?   
BTW many liquid/paste fluxes are rosin based and not synthetic at all. Of course they do have some additives to improve it's properties too.

[Ian.M]

For making DIY liquid flux, you want new pale rock-hard rosin, not half-burnt stuff you've inherited from your grandpa!

Crush and dissolve as much as you can in 95% or 97% alcohol, let it stand a few days and carefully decant the clear layer off the top for use, leaving any milky layer and solid bits at the bottom.   Add more alcohol and rosin to the remainder and put it aside for next time.

Its plenty active enough for fine electronics work and cleans off easily with alcohol (provided you decanted it properly).  I'd happily use it to 'hold' a cleaned board waiting to be soldered, but after you've soldered the board it isn't properly no-clean and don't apply it as a board laqquer afterwards.

Rosin (Colophony) fumes are known to be a respiratory tract irritant and health hazard. *ALWAYS* use adequate ventilation.  Activated Rosin flux can cause contact dermatitis - I found I had problems working on boards from a specific old TV manufacturer unless I fully cleaned the track side before working on them.

[Rasz]

and it smells fabulous, like somewhat a light incense, almost like a perfumed twig or something "green" 

enjoy your lung cancer guess what happens with you 'nice smell' once it goes into your lungs and recrystallizes there FOREVER


+1 what wraper said, this is the stuff we used in the eighties when we didnt have nice modern gel fluxes

[radix]

Yes, I forgot to mention that awful smell. And asthma. I also don't get why you are so enthusiastic about this.

[wraper]

I my childhood I had an allergy and no one could understand to what. Doctor made a test on my skin to different alergens, nothing made a positive result, my skin didn't react even to control chemical which should made a huge red blob on my hand (doctor was surprised). I even sprayed  strong hormonal anti allergy drug into my nose one time. In the end it turned out stat I had an allergy to rosin fumes  , I often soldered a lot to the extent that there was a fog in my room  .

[Refrigerator]

Well cigarette crap cleans out after 15 years shouldn't the same apply to rosin ? 
But i agree after not using the real brick rosing for years i just recently started using it again and oooh man all the childhood memories came back.
It's just like smelling that vintage TV set or  radio, there's just something special about the smell that makes me remember the good old days. 

[Ian.M]

As a liquid flux its effective and useful.  The solid block form - not so much. The health risks are manageable.

However the fact that you can make your own liquid flux from materials commonly available even in a 3rd world market, and if you thoroughly wash out and dry a cheap hiliter pen, can even make your own flux pen, opens up techniques like drag soldering SMDs to hobbyists, impoverished students and anyone who cant easily obtain the modern commercial liquid fluxes

[3roomlab]

For making DIY liquid flux, you want new pale rock-hard rosin, not half-burnt stuff you've inherited from your grandpa!

Crush and dissolve as much as you can in 95% or 97% alcohol, let it stand a few days and carefully decant the clear layer off the top for use, leaving any milky layer and solid bits at the bottom.   Add more alcohol and rosin to the remainder and put it aside for next time.

Its plenty active enough for fine electronics work and cleans off easily with alcohol (provided you decanted it properly).  I'd happily use it to 'hold' a cleaned board waiting to be soldered, but after you've soldered the board it isn't properly no-clean and don't apply it as a board laqquer afterwards.

Rosin (Colophony) fumes are known to be a respiratory tract irritant and health hazard. *ALWAYS* use adequate ventilation.  Activated Rosin flux can cause contact dermatitis - I found I had problems working on boards from a specific old TV manufacturer unless I fully cleaned the track side before working on them.

yes the fumes are quite irritating to me, i think it is also because this is maybe some high concentration ROSIN. i dont think i will ever know if this is activated or not. but with a large air removal duct, it should be a better scenario to work with. i dont think anybody have a electronics desk smack in the middle of green open field (i do know of someone who did it in UK ... in surrey lolz). i specifically use a NIDEC 24v centrifugal fan ( i think it is over 100cfm ) ... ducted to a spare washing machine draining pipe and it leads outside (thru a rough filter to condensate the flux, and no i dont want my neighbor to get colophony problems). i also just bought a "articulated arm" thingy so that i can attach and move this duct over what ever i am working on or what ever that needs fume extraction.

just curious... how much do you buy your alcohol for in your part of the world? and what kind do you buy? i have yet to see commercial tins of alcohol in my local hardware supply, or maybe it is something hidden otherwise on special request.

@ wraper. prolly both my irons are dialled down. but if brown = burnt, well then it is, but it look more like clear tea like brown or dark orange. not resembling the old electronics type of "toffee" candy murky brown. well it is exciting, i have not seen such clear flux. i wonder which is purer/cleaner, compared to the ones used for chinese orchestra instruments.

[smjcuk]

I my childhood I had an allergy and no one could understand to what. Doctor made a test on my skin to different alergens, nothing made a positive result, my skin didn't react even to control chemical which should made a huge red blob on my hand (doctor was surprised). I even sprayed  strong hormonal anti allergy drug into my nose one time. In the end it turned out stat I had an allergy to rosin fumes  , I often soldered a lot to the extent that there was a fog in my room  .

Similar here. They even stuck lots of sticky cups with allergens all over my back. Nothing happened. Went on a road trip around Europe for 6 weeks and the dermatitis cleared up. Lots of head scratching and I worked out that massive roll of multicore was the culprit, possibly the rosin cores. Have to lube up with emolients  before I solder; keeps it under control. That and I buy Loctite/Henkel solder instead which has different flux in it.

[wraper]

@ wraper. prolly both my irons are dialled down. but if brown = burnt, well then it is, but it look more like clear tea like brown or dark orange. not resembling the old electronics type of "toffee" candy murky brown. well it is exciting, i have not seen such clear flux. i wonder which is purer/cleaner, compared to the ones used for chinese orchestra instruments.

I still don't get your excitement about contaminating PCB with a huge amount of the flux which is hard to clean. I like my boards being clean.

[Ian.M]

It helps to know what denatured alcohol is called in your part of the world and what the denaturants are.  e.g. in many EU countries, its required to have blue or purple dye in it + other objectionable chemicals from our point of view.   In English speaking countries, the result is commonly known as "Methylated Spirits" (colloquially "Meths").  However in France their "Alcool à brûler" (alcohol stove fuel) is ethanol denatured with methanol and isopropanol with no legal requirement to dye it.  Its also about half the price of Meths in the UK at 2 to 3 Euro/L.

A small amount of water in the alcohol is not a problem when making flux. Colophony (Rosin) is only slightly soluable in water and you will get a murky milky layer settling out at the bottom containing nearly all the water.  As I said earlier, decant the good clear flux off the top, and you leave the water behind..

However if you do need very dry alcohol, any reasonably dry alcohol or blend of alcohols can be dried with anhydrous Calcium oxide to produce absolute alcohol (99.5% alcohol, 0.5% water).  Anhydrous Calcium oxide is commonly known as "quicklime" which can be produced by heating natural chalk (not blackboard chalk),  or white marble or white fine grained limestone to red heat and holding that temperature for at least five minutes.  Quicklime is highly caustic and a severe skin contact and inhalation hazard and its reaction with water is highly exothermic so you'd better know what you are doing before even considering making it.   

Add the granular or powdery quicklime *SLOWLY* to the alcohol, monitoring the flask temperature and allowing it to cool as required.  Agitate several times then seal and let it stand several days till as much of the solids as possible have settled out.  Decant and filter to remove the rest.

Calcium and magnesium hydroxides are generally reckoned to be insoluble in alcohol so the resulting alcohol will be dry and acceptably pure.  It can be tested for water content using freshly dried Cobolt chloride paper, which should stay blue.

Alcohol can also be dried with salts, including common salt (Sodium chloride) which dissolve in the water to form an immiscable layer that can be separated from the alcohol.  However I don't want my flux or boards contaminated with traces of chlorides or sulphates so even though its a lot easier and safer I don't suggest that.

[3roomlab]

ok meth spirit, i think i know where to get that. but for now, i will just up the power of the fan suction !  ... it is beginning to sound like a vac !

i think if coating PCB with it is keeping it "clean", if it works, i certainly have not yet tried this trick. im sure there are many ways to keep PCB clean, some even like it buck naked 

[Ian.M]

As I said, Meths usually has crap in it you don't want on your boards.  I've used it before to make liquid flux but its not recommended.

If your local meths is died blue it contains die (probably aniline dye) and if it leaves an bitter residue after a drop of it has dried on your fingertip, it contains a bittering agent  (probably denatonium benzoate or denatonium saccharide) to try to stop the alkies killing themselves with it.  Both will decompose at soldering temperatures and may shorten your tip life. 

Additives that are volatile organics aren't such a big deal as if you use the flux sensibly, all but a trace will have evaporated off before soldering.

[Balaur]

I still don't get your excitement about contaminating PCB with a huge amount of the flux which is hard to clean. I like my boards being clean.

It was very useful back in my youth with the bare copper traces and no mask.