Phosphoric acid

[Torqu-E-Cycles]

I don't understand the data sheet for the spectral under 385 epoxy primer, I'm not that clever when it comes to what the surface should be sanded with, why can't they just say knock it down with 120 grit haha

 

[Morris]

Thats awesome how did you get it to strip the rust so quick!! I spent an entire day on one area and it came out probably about half as much as yours. I've spent the day welding up roof corners that were full of filler but I will dilute down to about 40% tomorrow and see if it speeds it up, just tap water?

Keep it wet and agitate it, I use a toothbrush size stainless wire brush. That was a 30% solution. I find that strong concentrations don't seem to wet as well.

 

[Torqu-E-Cycles]

I will get a stainless brush as all of mine are plated steel, thanks!

 

[Torqu-E-Cycles]

Morris, you are spot on! The acid i have is 85% concentration and wasn't performing very well, slow at working and fast drying out.

Diluted 50/50 to around 40% and magic! Works literally twice as fast! The irony that adding water helps remove rust haha!

 

[Torqu-E-Cycles]

I love phosphoric acid! Not quite finished, but using my technique of soaking kitchen towel and leaving on the panel overnight is helping, in the morning I lift it off, give a good wire brush, wipe the brown away then put the soaked towel back on until I get back from work, its literally rust removal while you sleep!

 

[Screwdriver]

Saw an interesting video about NASCAR cheats the other day. One chap would have his "stock" car acid dipped. Leave the entire shell in a bath of acid until the panels were paper thin. Apparently saved hundreds of lbs of weight. Maybe you'll be so lucky.

Sleep tight!

 

[Torqu-E-Cycles]

Saw an interesting video about NASCAR cheats the other day. One chap would have his "stock" car acid dipped. Leave the entire shell in a bath of acid until the panels were paper thin. Apparently saved hundreds of lbs of weight. Maybe you'll be so lucky.

Sleep tight!

Slightly stronger acid i can imagine! I've left a bit of steel that I cut out of the shell in a tub submerged for a week and the only thing thats happened is its super clean

 

[dieselsamurai]

Awkward shapes i mix phosphoric acid with wallpaper paste granuals just slap it on and wash it off after a day

 

[Torqu-E-Cycles]

Awkward shapes i mix phosphoric acid with wallpaper paste granuals just slap it on and wash it off after a day

Thats a good idea! Do you have any problems with it drying out or not getting all the deep rust out?

 

[Ross365]

Saw an interesting video about NASCAR cheats the other day. One chap would have his "stock" car acid dipped. Leave the entire shell in a bath of acid until the panels were paper thin. Apparently saved hundreds of lbs of weight. Maybe you'll be so lucky.

Sleep tight!

Don't think that would be phosphoric, which reacts by forming a protective layer of iron phosphate on the steel. Think it would have to be nitric or hydrochloric to eat the steel away and even citric will very slowly dissolve steel.

The observation that 40% phosphoric removes rust twice as fast as 80% acid reinforces the view I've expressed previously that phosphoric behaves in a complicated way, and especially on the subject of whether or not to wash after use seems always to be the subject of debate.

 

[Screwdriver]

I was kidding.

Tough crowd tonight...

 

[dieselsamurai]

Thats a good idea! Do you have any problems with it drying out or not getting all the deep rust out?

If its hot weather or outside worth covering in plastic but if its cool or in the workshop i dont bother , i just jet wash off after a day or so. I find if you can aggitate it with a brush every so often it reaches all the surfaces fine

 

[Morris]

Saw an interesting video about NASCAR cheats the other day. One chap would have his "stock" car acid dipped. Leave the entire shell in a bath of acid until the panels were paper thin. Apparently saved hundreds of lbs of weight. Maybe you'll be so lucky.

Sleep tight!

In the 60's the Chrysler factory built Super Stock drag cars were acid dipped to reduce weight. They built 47 I believe, very valuable today.
Ford built lightweight Galaxy 's for the same class and acid dipped parts. All allowed at that time.
It was a really interesting period of drag racing history.

 

[Screwdriver]

 

[Morris]

Wicked Wednesday: Chrysler Factory Lightweight Drag Racing Warriors

Chrysler built a series of factory lightweight drag cars in the 1960s to help them "win on Sunday and sell on Monday."

dodgeforum.com

Going OT now but a subject I am very interested in.

 

[Onoff]

Making the garden arch and it was fiddly when paint stripping the completed frame. Before welding I just locally cleaned back to bare metal. Thinking I'd be better to paint strip the lengths of box section first. If they had a "protective" coat of 10% phosphoric acid, would that affect the weld?

 

[Morris]

Seems to weld ok for me. Great thing is that after a 10% treatment it stays rust free for weeks which is great for welding.

 

[Onoff]

Seems to weld ok for me. Great thing is that after a 10% treatment it stays rust free for weeks which is great for welding.

Is that a 10% wash after first having had a 40 or so % derusting application?

 

[Morris]

Is that a 10% wash after first having had a 40 or so % derusting application?

Yes it is.

 

[Torqu-E-Cycles]

I'm having an issue on the mini roof, after using the acid as we've discussed, washing off with clean water and completely drying then buzzing off with 120 and epoxy priming I'm getting brown rust stains creeping out of the seams! I only painted it 48 hours ago and it's in the dry.

Surely if there was some acid hiding in the seam crevis it wouldn't cause rust as thats why we are using it on the first place?!

Out of the entire roof there's 3 spots which are tiny, the size of a match head but they're clearly coming from between the 2 sandwiched seems ☹