how to improve flux wetting?

michael080

Western Thunderer
Hi,
I am using 20% phosphoric acid as flux and love it after testing many other agents.
However, I am not happy with the wetting capability. I tends to form local drops on brass, even if the brass has been degreased with acetone before. Technically, it has a high contact angle on brass.
Is any of my fellow thunderers using a wetting agent with phosphoric acid to improve wetting?

I have been testing ox bile, but the result looks ghastly. :eek:

As some may know, I am not UK based, so brand names won't help much.

thanks for your input.

Michael
 

simond

Western Thunderer
worth looking at citric acid too, if you have not already tried it. I use it in saturated solution with water, and ipa added, approx 30% by volume. Im told that this might be too much ipa, but it does wet the brass.

atb
Simon
 

neaston

Western Thunderer
I think you can reduce the concentration by half. I've been using it at 10% for about fifty years with no problems at all.
Never had a problem with wetting I just apply it along a short length of the joint with a bit of wire.
Nick
 

SimonT

Western Thunderer
Nick,
that is useful information as I have followed SimonD's path. I was amazed to find that citric acid flux worked to solder steel rail, so no more of the nasty Carr's Green. The only problem is that it leaves a sticky residue that needs to be washed off to do any cleaning up. Warm water a washes it off but a thinner solution might reduce the need for the trip to the sink.
Simon
 

simond

Western Thunderer
Nick,

thanks

Which concentration? Citric or alcohol?

Sounds like a martini! Shaken or stirred, sir?

Atb
Simon
 

Deano747

Western Thunderer
I have recently purchased some 45% phosphoric acid and by mixing 10ml acid to 25ml distilled water gives me 15% (14.7% to be precise) and I added 5% viakal as a wetting agent which may help prevent corrosion. Early days yet but seems to work ok so far. Will report back in due course.

Regards, Deano.
 
Top