16 replies to this topic

[Roderick Armstrong Sr]

I can not seem to get a straight answer to this question. I successfully use the Ajax-and-water method.

 

Can you neutralize acid flux, after soldering, with lighter fluid?? I have seen two posts briefly mention using a method such as that, but no details. 

[mreibman]

It's acid. Neutralize with a base, like baking soda.

Clean with Ajax like you're doing, or alcohol. Or insert preferred cleaning method here.

[Bill Seitz]

Soldering heat should neutralize most of the flux. An alkali (base) will neutralize any remaining. The abrasive cleanser (Ajax) is alkali, so it both neutralizes acid and polishes away any other contamination or discoloring, and with the detergent, washes the parts clean. Paste fluxes have the acid mixed in some sort of paste base which has to be cleaned off with a solvent or detergent. The popular Nokorode use petrolatum for the paste, and this requires some extra cleaning effort to get all the excess petrolatum and burned residue off.

 

Lighter fluid, which can be petroleum distillates or naphthalene depending on the brand, won't neutralize acid, but it does clean off the other contamination well. Most acids can be rinsed off in water, so a thorough soap (also alkali) scrubbing and water rinse and drying will also work.

[Roderick Armstrong Sr]

Mike and Bill, thank you hobbyist's : I Now Have My Answer !!

[slotcarone]

The easiest and what I consider the best method is to bring the chassis parts to your sink and scrub with an SOS steel wool pad. This gets rid of any residue and also polishes the metal for a finished look or to get it ready for the next soldering part of the chassis build. Do not use Brillo!

[Dave Crevie]

After some 50 years of building brass locomotives for model railroading I can unequivicably say using denatured alcohol for clean up of acid flux is best. Followed by polishing with abrasive cleaner like Ajax or toothpaste. If you don't want to get the whole part wet, a paste of Arm and Hammer baking soda and water can be used to neutralize the acid. Apply with a small brush, then rinse off with that brush dipped in plain water.

[Bill Seitz]

Be very careful with denatured alcohol, or metholated spirits as the Brits say. It contains methanol which is not only poison to humans, it corrodes aluminum and maybe magnesium as well. Isopropyl Alcohol is safer, but the watered down variety at the pharmacy will rust steel. I get 99% Isopropyl at Ace Hardware.

[MG Brown]

I use this- it can be sprayed or brushed.

 

[team burrito]

i heard windex works good - i also use acetone & a q-tip to get off stubborn stains.

[swodem]

Why would solvent neutralise an acid?
It would only dilute it, like water would?


I would use mild alkaline to neutralise


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[NSwanberg]

Does water neutralize acid or just dilute and rinse it away?

 

I find lots of Naphtha or lighter fluid will rinse the acid off.

 

Someone here suggested cleaning frames with orange hand cleaner. I like that best now.

 

Ajax and Comet dull the solder.

 

If you are using liquid acid flux some of it seems to vaporize and then deposit to other places on your work. Rinse it off!

 

If you want the solder to stay nice and shiny do whatever Jairus does?

[slotcarone]

If you all would try my SOS pad and water in the sink method you will see just how well it works to remove any residue and also polish the metal without scratching it. Of course dry it well with paper towels.  I also follow up with a fine metal polish between steps and when the chassis is all finished. This keeps the rust away.

[MSwiss]

Nelson hit on a big problem.....the fumes.

I have casual racers come in all the time with RTR cars, both "factory" and custom, with rusty axles.

During Covid, I had one guy come in what a car that hadn't been run for months.

When he put the car on the track and hit the trigger, the motor immediately smoked from the axle being rusted in the bushings.

I always keep a wet rag and a small reservoir of water in my work area to douse and wipe down the whole area being soldered.

[JerseyJohn]

I have a spray bottle filled with a backing soda and water solution. Baking soda neutralizes the acid. I will spray the chassis and jig numerous times through out building .Nothing locks up a hinge quicker than acid...

[Eddie Fleming]

I have a spray bottle filled with a backing soda and water solution. Baking soda neutralizes the acid. I will spray the chassis and jig numerous times through out building .Nothing locks up a hinge quicker than acid...

 

What is your ratio for the baking soda water mix?

 

I know it is not critical.

[JerseyJohn]

A few table spoons per quart does the trick, Once the foaming stops i give everything a quick rinse under water.

[MSwiss]

There is a cute YouTube video for cleaning up flux on a large item that has been soldered with a torch.

 

After the solder has cooled, he hits it again with the torch for a split second or two,just to get it a bit hot, and then sprays a mist of water on it.

 

It steam cleans off the residue.

 

Lots of replies about how it's a bad idea,(thermal shock, etc.) but for the items show, it might be OK.