Post cleaning flux residue - silver brazing

[crueby]

One time I tried the brick cleaner - worked great, but I stored the jug indoors, and THEN found out that the seal in the cap was not the best, and it was leaking fumes. Nasty smell, and it ruined some metal parts nearby. Thats when I went back to the sparex or vinegar - slower but safer, at least in an indoor shop.

[Jo]

Mine is in a plastic dustbin outside 

Jo

[crueby]

Mine is in a plastic dustbin outside 

Jo

Perfect!

[Jasonb]

Brick cleaner is readily available and is a low percentage of Sulphuric acid. Don't use drain cleaner as that is normally Hydrochloric acid (so beloved as a household cleaner until the cleaner drops their damp cloth onto marble floor tiles  )

Jo

The brickcleaner I use is Hydrochloric, as are most others. Works for me

[Kim]

I use both the Harris White and Black fluxes. They came premixed in a plastic screwtop jar.  And for both of them, I add regular tap water when they start to dry out.  As Chris said, they dry out even with the lid on.  And there may have been a time or two when someone forgot to put the lid on the flux before they went in for the day and things REALLY dried out then ... oops...  But adding water and stirring it in revitalized it, and it still works just fine.  If you get too much water in it, just wait a few days, and it'll be back to the right consistency again.

Kim

[petertha]

I was hot on the trail to pick up some Sparex #2 pickling compound which is available at my local jewelry supplier. Then I read the fine print - only recommended for non-ferrous metals. They are not referring to using the same pickling bath for both metal types, I take they mean not recommended for steel at all. Apparently there is a Sparex #1 for this but it seems to be unobtanium where I live. I probably will get #2 anyway, but it may be back to the original plan of diluted muriatic acid or similar.

https://www.krohnindustries.com/cleaning-agents/sparex/

What I REALLY could use is a miniature sand/media blaster blaster sized to my small 2-ish HP compressor. Any normal sand blaster requires relatively high CFM flow rate + high pressure = high(er) HP & tank volume. At the opposite end of the spectrum I tried one of those airbrush styles with very fine media, even baking soda. It was anemic. Fine for polishing the edges of coins on a good day. Am I missing anything useful in terms of an in-between sized tool? I have seen some that would look at home in a nuclear lab because of the cost.


Video covers basics of Sparex but its copper & brass example
<a href="https://www.youtube.com/watch?v=-LTU9vfWMFI" target="_blank">http://www.youtube.com/watch?v=-LTU9vfWMFI</a>

[crueby]

The sparex nbr 1 is no longer made, only the nbr 2. What I do now is just keep one container of nb 2 for brass and its alloys, another for steel. Works fine.

[petertha]

Oh, good to know, thanks for that.

[Jasonb]

I've only got a 2HP compressor and use it with a cheap Lidl spot blaster and it does model parts OK.

This was after pickle, part is about 200mm long



And after





This is larger than one of your cylinder jugs will be.





Those were with grit but with glass beads it leave sa nice finish on non ferrous to remove machining and abrasive marks.

[crueby]

That does a great job!  That gun needs about 11 CFM to run, it looks like? My little compressor will only output about 2 CFM, works with the little airbrush style blasters, but that type takes forever on anything but tiny parts. Maybe I need to invest in a bigger compressor...

[Jasonb]

My compressor actually only puts out half that but works OK

https://hyundaipowerequipment.co.uk/hyundai-50-litre-air-compressor-1cfm-100psi-oil-free-low-noise-electric-2hp-hy27550?absrc=Google&abid=&abcampid=23076824789&abgroupid=&gclid=CjwKCAjwjffHBhBuEiwAKMb8pETqHl-eD7yh6S7L8DlHpOriseut4ll3wrRcRFXZF7IQfYJ5VxUwxxoCGNcQAvD_BwE&abkwdid=&tw_source=google&tw_adid=&tw_campaign=23076824789&gad_source=1&gad_campaignid=23076826748&gbraid=0AAAAAC96wz5lynYYDsx_gX1umCp2DLcAN

[petertha]

Those are excellent sand/bead blast results. Like crueby I was going off the gun CFM specs sprinkled with a few weekend warrior YouTube videos. I was prepared to compromise on my smaller compressor & go about it in more frequent, shorter duration intervals. But I was under the impression if you only had fractional CFM rating at specified pressure the gun would not deliver or basically work at all. Interesting. Well, hard for me to justify a big compressor but never say never. I sold a vertical tank 4HP years ago which had decent power. However it was the older slapper valve style & noise level was just deafening. I replaced it with a much smaller SilentAir, suitable for many small jobs & runs the HVLP guns. The list price of big boy compressors is rather shocking.

https://www.kmstools.com/air-compressors/stationary-air-compressors.html?srsltid=AfmBOoqWBqd1ZEeF9SsP3EuS1BmYF-X2khnnCSn8fOptf1PKBxZU5i7G

[crueby]

Hi Jason,
Looking at the specs on that compressor, looks like it will deliver 11cfm from the tank but can only replenish it at half that, so if you do short sprays you can keep up at the 11cfm rate. On the smaller compressors like mine, the tank/regulator will only deliver 1.5cfm or so.

[Dave Otto]

I was going to say early on about my preferred method, which is to boil the part in water, which will remove the glass hard flux residue and then bead blasting with very fine glass bead. I thought that the original question posted did not want to hear about solutions that included blasting. Anyway that is what works for me and the mostly small parts and assemblies that I do, no boiler making going on in my shop.

I built my little blast cabinet years ago, the upper part was surplus from work, it was some specialized micro blaster for cleaning high vacuum components, I only got the sheet metal box and glass. I built the frame and lower hopper added the gun and foot pedal. Some years later I picked up the nice stainless cyclone from a high tech surplus outfit here in town.
It has served me well and my 5hp single stage compress is able to keep up just fine.

Dave

[Jasonb]

Hi Jason,
Looking at the specs on that compressor, looks like it will deliver 11cfm from the tank but can only replenish it at half that, so if you do short sprays you can keep up at the 11cfm rate. On the smaller compressors like mine, the tank/regulator will only deliver 1.5cfm or so.

Careful, many small compressors quote the displacement probably as it is the higer value to attract buyers. if you look at the spec the FAD (Freel air delivery) is half that and the truer output.

Larger bits you do sometimes need to allow the tank to come back upto full pressure but smaller stuff I don't really need to.