What flux for soldering old brass?

Pbassred · 4th December 2007, 10:24 AM

I have a big old MOSFET amp with T-03 devices screwed into brass bushes which in turn ar soldered onto the PCB. After a 1/4 century of rock and roll the solder arround the bushes is cracking, so I'm cleaning and resoldering.

What is the best flux for that?

fizzard · 4th December 2007, 03:08 PM

Plumber's flux works pretty well on brass, but I've always read that it doesn't mix with electronics. I've never tried it myself. The zinc in brass oxidizes quite quickly, so a more potent flux is required for soldering.

Mitch Alsup · 4th December 2007, 08:51 PM

I have always had good luck with the wattery flux that comes with silver solder when tin-lead soldering brass to steel or copper.

unclejed613 · 4th December 2007, 09:13 PM

an aspirin tablet (NOT ibuprophen or acetaminophen, or containing caffeine) works as a good flux for brass or even steel (not stainless steel). since it is a mild organic acid (salicylic acid) it must be cleaned off with hot water. also, the fumes are very irritating but dissipate quickly, so use with adequate ventilation and keep the flux smoke away from your eyes and nose (a small computer fan will do fine).

AndrewT · 5th December 2007, 09:32 AM

Quote:

Originally posted by unclejed613
an aspirin tablet .... works as a good flux for brass or even steel (not stainless steel). since it is a mild organic acid (salicylic acid) it must be cleaned off with hot water.

dissolved to make a saturated solution or applied as a powder and melted with the heat?

Juergen Knoop · 5th December 2007, 10:35 AM

I'm very fond of oldfashioned colophony based flux.
It is claims to be non corosive and does not smell to bad.

http://www.loethonig.de/
Regards

4th December 2007, 10:24 AM	#1
Pbassred diyAudio Member Join Date: Nov 2003 Location: N London	What flux for soldering old brass? I have a big old MOSFET amp with T-03 devices screwed into brass bushes which in turn ar soldered onto the PCB. After a 1/4 century of rock and roll the solder arround the bushes is cracking, so I'm cleaning and resoldering. What is the best flux for that? __________________ Jeeees! I only asked www.davethebass.com

4th December 2007, 09:13 PM	#4
unclejed613 diyAudio Member Join Date: Dec 2006	an aspirin tablet (NOT ibuprophen or acetaminophen, or containing caffeine) works as a good flux for brass or even steel (not stainless steel). since it is a mild organic acid (salicylic acid) it must be cleaned off with hot water. also, the fumes are very irritating but dissipate quickly, so use with adequate ventilation and keep the flux smoke away from your eyes and nose (a small computer fan will do fine). __________________ Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net spammer trap: http://www1284177414881.v-dc.net/

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
How do you remove flux residue after soldering?	777funk	Construction Tips	40	25th September 2010 11:31 AM
Brass sub box	Piglicker	Subwoofers	12	19th June 2006 12:33 AM
FS: Rega tonearm VTA nut (brass)	krishu	Swap Meet	0	2nd November 2004 04:16 PM
UK Source for brass bar?	penance	Everything Else	6	4th October 2004 10:49 AM
Brass Buss Bar	kilowattski	Solid State	6	12th October 2003 07:06 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

4th December 2007, 03:08 PM	#2
fizzard diyAudio Member Join Date: Nov 2006	Plumber's flux works pretty well on brass, but I've always read that it doesn't mix with electronics. I've never tried it myself. The zinc in brass oxidizes quite quickly, so a more potent flux is required for soldering.

4th December 2007, 08:51 PM	#3
Mitch Alsup diyAudio Member Join Date: Aug 2007	I have always had good luck with the wattery flux that comes with silver solder when tin-lead soldering brass to steel or copper.

5th December 2007, 10:35 AM	#6
Juergen Knoop diyAudio Member Join Date: Jan 2007 Blog Entries: 3	I'm very fond of oldfashioned colophony based flux. It is claims to be non corosive and does not smell to bad. http://www.loethonig.de/ Regards

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)