[TimmyMac]

I picked up a little jar of this vaseline-consistency soldering flux, and I want to make it liquid. Other than heating it up, which is a pain, is there any solvent I could mix to dissolve it and use in a bottle with a needle?

 

[MisterX]

Alcohol but you have to watch how far you thin it down or it will "burn off" to fast.

 

[TimmyMac]

I tried 95% ethanol, it's not miscible. What about isopropanol? Did someone sell me vaseline?

 

[srserl]

I like the paste flux and use a small paint brush to spread it on where I want to solder. I also dip my iron directly in the paste flux before cleaning it in the brass thingy. I also have liquid, but only use it when I want to get just a touch of solder for soldering smd.

 

[cfcubed]

You guys may know this, but I really like using "Bottled rosin flux" that I purchased w/some other stuff from Tangent's shop. It does just what I want... Just need to keep a little pin around to clear the very tip if not used for a while.

 

[qusp]

yeah I use the cardas rosin flux paste. works a treat; I too prefer it to the spray liquid I have. I also find its great for helping keep a component or wire in place while I solder it.

 

[compuryan]

I just get the solder that has a rosin core flux. It does everything I want it to and allows me to work quickly. Paste or a flux pen would just get in the way IMO.

 

[DaMnEd]

Quote:

Originally Posted by compuryan /img/forum/go_quote.gif I just get the solder that has a rosin core flux. It does everything I want it to and allows me to work quickly. Paste or a flux pen would just get in the way IMO.

For through hole soldering most would agree that rosin core solder is enough, but surface mount is a completely different game, specially since many of the techniques require you to tin the tip, and then apply that solder in the tip to the component, by that time all the flux was burned.

And swipe movement techniques also benefit greatly because with flux bridges are much less common, the flux helps immensely in distributing the solder evenly.

 

[mono]

Liquid flux (ignoring the newer acid/water based type) is rosin dissolved in alcohol. Alcohol will not dissolve the petroleum base used in typical paste flux.

Gasoline or other petroleum solvents should work, but have too much evaporative fuming and are flammable. You're best off just using it as-is, apply it with a soldering pick if necessary and let the heat of the iron melt and spread it as was intended, or of course buy some liquid flux instead.

Paste solder can still be used for swipe soldering, you typically just need to make a swipe-pass one time to flow the flux then a second time with extra solder tinning the tip to solder the part down. It may be more trouble than it's worth to bother with this though, considering the cost of the projects and that a bottle of liquid flux is under $10 and lasts a long time if used sparingly.

Whether the flux already in flux-bearing solder is good enough depends on the joint, how oxidized the metal is, and what % of flux is in the solder being used. Personally I prefer to add flux when not in a hurry, because it tends to make the joint at least as good if not better and because often people put more solder than necessary on a joint only because they had to apply that much to get enough flux on the joint. Most people use maybe 2X as much solder as a joint actually needs and solder (especially lead bearing with lead prices rising over the past couple years) is more expensive than flux.

 

[DaMnEd]

Cheap liquid flux can be found here: DealExtreme: $2.12 Goot Super Soldering Flux

 

[mono]

Quote:

Originally Posted by DaMnEd /img/forum/go_quote.gif Cheap liquid flux can be found here: DealExtreme: $2.12 Goot Super Soldering Flux

Don't bother with their paste flux though, I have some and it doesn't work well at all, might as well just spread vaseline on the parts.

 

[DaMnEd]

Quote:

Originally Posted by mono /img/forum/go_quote.gif Don't bother with their paste flux though, I have some and it doesn't work well at all, might as well just spread vaseline on the parts.

Did you try the liquid kind on my url? I am probably going to buy it anyway, just too see, but It would be nice to see some confirmation (other than the reviews on the page) about its effectiveness.

 

[mono]

No I've never tried it... I mean bought from them. Maybe when I run out or place another order there.

 

[TimmyMac]

Quote:

Originally Posted by mono /img/forum/go_quote.gif Don't bother with their paste flux though, I have some and it doesn't work well at all, might as well just spread vaseline on the parts.

Their paste flux is really only useful for cleaning tips, not much else - that's the one I'm trying to get into liquid. Their solder works fine though, and is dirt cheap at under $10/lb with free shipping. I guess for SMD I'll have to deal with a toothpick, or just use solder paste and be done with it.

 

[mono]

I've used different paste fluxes that worked ok but theirs seems too mild to even clean tips unless all the tip needed was some wetness to slush off crustly remnants of prior flux.

For those in the US, Tangent still has liquid flux in a nice applicator bottle. Tangent’s Parts Shop Elsewhere, MG Chemicals seems to sell one of the more popular liquid rosin products in small quantities, though that might also vary geographically.