Frame finishing

[Akula]

I’ve stripped a trek 970 but a lot of surface rust and also putting , particularly around the BB. It’s my misses bike and she wants it recoated. Asking around locally (Singapore) and one person has suggested a place across the border which has some kind of dipping process to neutralise rust ( potentially I’ve got some inside as well). The comment was also that it will reduce weight and this is already a light frame so don’t want to weaken it) .

Anyone have any thoughts on dipping , or other ways to neutralise rust to Ensure my work won’t be in vain

 

[Paul R]

I just sprayed clear spray grease down my tubes its worked on the underside of cars for me in the past. there are many rust treatments out there you cando at home but ive not tried them sadly.

Get the pitting as good as you can with a wire brush on a dremmel then etch primer it all, high build primer next especially on the pitting. Sand back smooth with fine sandpaper. Then you can paint

 

[Akula]

Re:

Was originally planning on a powder coat, but a good paint treatment might be wiser I guess

 

[Bert the Weldor]

Re:

Just to clarify, I'm certainly not the holder of the last word on rust removal, but, I cause rust almost daily! I've been a welded steel artist/sculpture (hate saying that out loud) for about 15yrs. I mostly do rust patina and clear coat on my kelp(a type of seaweed) sculptures. I have my own formula for causing instant rust, but have done quite a bit of rust removing as well.For reference, my website: http://www.wingnutdesigns.com. (Mods: Hope it's ok to post this, if not, please remove with my apologies)
Here's my 2 cents:
You could dab the rust spots with Muriatic Acid then neutralize with baking soda and water. The acid with eat the rust right off. But this is very, very strong acid so baby steps. This is dangerous stuff so do your research on it before using. You need full PPE. This s**t will absolutely kill you if you f**k up.
More gentle would be trying vinegar. Weaker so will need to soak the rust longer, but will eventually take it off. Problem with any acid is it goes after the good metal too, but not as fast as it eats the rust.
You can get rust converters which you glob on and it converts the rust to a different, more stable material. But, it doesn't remove it. I think most can be primed and painted.
Better and more efficient would be a grinder/ rotary tool/die grinder and a steel wire wheel. But take care again, as you'll take a bit of the good stuff with the rust.
Best would be soda blasting. You can buy little homer guns or get the whole frame done with a bit more attention to the rusty pitting. It will be clean as a whistle after that(and you'll want to put a light oil on it until painting as it's going to flash rust pretty quick unless you're in the desert....) Walnut shell, glass bead, Alum. Oxide, etc could be used too, but that's for a pro to do. The courser harder blasting media can not only really strip your metal away fast but using at too high pressure could/will distort your frame. (It's like millions of mirco ball peen hammer blows)
Once blasted clean, paint or powder coat.
If you want the pits filled, a light auto body filler and very fine sanding IF you're wet painting, NOT powder coating.
If powder coating..... a little secret, non welding/brazing fix is the original J B Weld. Not the other types of J B Weld, only the Original is powder coatable. (There may be other brands that will work with PC, but I only know of this one, and I know first hand the other sub types of J B Weld don't work.....)
You can use this to fill the pits and sand smooth once cured. It's tough stuff, but it will take Powder Coat.
Anyhow......that got long winded........but that be to no ones surprise............ XD!
Good luck!

 

[Akula]

Re:

Thanks very helpful. I have spent quite a bit of time with rotary wire brushes , Drexel’s getting worst of it out , but worried about the nooks and crannies I can’t get into . Looks like they need a chemical treatment, likely vinegar

 

[Miano]

Re:

Hi there,

Have been to Singapore before and still have a couple expat friends up there. Nice place to be and to visit.

Talking about the issue on the table, I would encourage you to study further and eventually to try an electrolysis process, that will convert the rust (iron oxide) onto O2 and Iron without eating the tubing.

This is safer than vinegar from the material integrity point of view, even though the process is a bit messier.

DISCLAIMER: FOLLOW THE PROCESS BELOW AT YOUR OWN RISK. I am no engineer but you may want to consult one to confirm calculations (or YouTube, perhaps). MAKE SURE YOU STAY OUT AND AWAY FROM THE FUMES COMING FROM THE PROCESS (NOT MORTAL BUT DANGEROUS ON THE LONG RUN).

Materials needed:
- Kids inflatable pool (you could make the front portion of the frame first and then the rear portion on the next cycle; does not to fit an entire frame in the pool at once)
- Salty water (to the saturation point for improved electro-conductivity);
- Strong DC font (could be a car battery charger OR a notebook font);
- "Sacrifice" Metal bar (to serve as cathode "+" and will be completely rusted after the process is concluded).

Process:
- Find an open space, well ventilated and out of reach for children and unaware people in general;
- Make sure the frame is free of grase, oil and dirt in advance; Put it in the pool;
- Pour the saltywater onto the pool, enough to cover the part of the frame to be treated;
- Connect the Positive DC "+" output from the font to the Sacrifice Metal;
- Make sure the sacrifice metal does not touch the frame by any means (otherwise the font ... BOOM!);
- Connect the Negative DC "-" output from the font to the frame;
- Connect the font to an AC outlet;
- A brown, ugly and smelly waste will show up floating in the pool. Do not panic, it is absolutely normal. The frame will not be melting under it.
- Check every 3 hours and you should be good after 12hrs or so.
- After this period, you may want to inject rust remover and then grease which could be in liquid of powder form.

If the process sounds scary to you, you may want to try it in a smaller scale with bolts or other rusted tools in a bucket just to test the idea and to understand how it works.

Good luck !