PDA

View Full Version : Evapo-rust Questions?



Black_Moons
06-13-2010, 02:06 PM
Hi, Just started using evapo-rust to derust some hardware and parts for a 14" beaver wood bandsaw and have a few questions.

1) it seems to leave some blackness where rust has eaten away the metal.. of course this might be because allready my solution is super dark from use. How do I get it to leave a peice a uniform color?

2) How dark can the solution get before I should change it? Right now I can only see about 5mm into the solution in low/moderate lighting before parts disappear.

3) Should I rinse derusted parts in something ASAP? they seem to be turning a sorta grey color (the black spots turn a darker grey) a few mins after drying.

4) How can I remove this greying? Id like solutions for critical dimention parts like guiderails and ways and solutions for non critical parts like brackets.

5) Can parts be left too long?

6) I tossed some aluminum parts in to get rust stains off, but after removing them after an hour or two they seemed to have a lot of white aluminum corrosion (Unsure how much if it was there before the parts went in), Was this a reaction with the steel parts in the tank? (Stainless steel bowl for holding parts/solution), or was this just existing aluminum oxide becoming hydrated and expanding?

Lew Hartswick
06-13-2010, 04:12 PM
What are the chemicals in it? Then maybe the activity with various
metals can be determined.
...lew...

lakeside53
06-13-2010, 08:46 PM
The dark or black color is simply carbon from the rusted steel... scrub it off with scotchbrite. If you want it "shiny", buff it with a non-abrasive.

Dirty solution - it can get very dirty and still work. If in doubt, use the dirty stuff for rough work, then swap the parts into cleaner solution. I use the old stuff until it's sludge.

After derusting then washing in clean water the part is prone to instant flash rust. Dip it in clean evaporust and let dry, or polish and oil.

You can leave iron/steel parts in as long as you like .. unless they are only partly submerged. If so, the air/solution interface will cause erosion in a "line" due to the continuous rust/removal process happening along the meniscus.

I've never had any problems with aluminum, paint, plastic, mixed materials or whatever even when left overnight at elevated temperatiues. I wouldn't push it though if you have degraded solutions heavy with removed iron oxides.

Kenwc
06-13-2010, 08:58 PM
As stated...the black is "ok" (and it's actually a good thing and not a bad thing) and after rinsing with water and drying, you can prime and paint right over it. I was told this by a tech at Evaporust a few weeks ago.

He also told me it will speed the process if you can get the E/R solution up to about 90 degrees. I tried that and it worked great and actually had less of the black.

I swear by Evaporust now and have had a lot of experience with it.

I just recently ordered another product of theirs called "Rust Bandit"...it protects from the flash rusting for up to 12 months or when you decide to rinse it off and apply top coats.

When it gets dark I filter it into another jug...I get rid of it when it's no longer effective.

I always do a wipe down with acetone before priming.

lazlo
06-13-2010, 11:11 PM
2) How dark can the solution get before I should change it?

It takes increasingly long to de-rust, as it changes from yellow to black. I usually discard it when it stops showing a noticable change in 15 minutes, which is usually a dark amber syrup color.


3) Should I rinse derusted parts in something ASAP? they seem to be turning a sorta grey color (the black spots turn a darker grey) a few mins after drying.

EvapoRust gunks up and turns gummy if you don't wash it off. Leave a small sample of plain EvapoRust in an open container -- it turns into a bubble-gum like material :)


How can I remove this greying? Id like solutions for critical dimention parts like guiderails and ways and solutions for non critical parts like brackets.

5) Can parts be left too long?

I find that parts will turn grey if you leave it in the EvapoRust too long. You're pretty much guaranteed the grey patina if you leave it overnight. It seems to vary according to carbon context (mild steel or cast iron) and hardness, but I haven't figured out the correlation.

I like to leave parts in 12 hours at most. You usually won't get the grey coating (which doesn't brush off) if you leave the parts in shorter than that.

JRouche
06-15-2010, 10:04 PM
Ive used alot of various rust converters and that stuff is tops on my list. Besides my ten gallon bucket that I use electrolysis rust removal for. Thats still the best.

I have four gallons of it in a tank and never re-new it or change it. Still working strong after ALOT of parts and three years.

Yup, there is a sludge layer at the bottom of my tank. No biggy.

It washes right off the parts. For a part that Im NOT gonna paint anytime soon or use another rust preventative coating like bluing Ill just rinse with water and dry it off. It leaves kinda an oily or greasy coating on the part. Its not oil or grease, but acts like it. Kinda repells water. And I wouldnt paint over it because it is a loose coating, not part of the metal and not adheard to it either.

If Im gonna paint or coat the metal really soon after de-rusting Ill wash the part in soapy water. Dawn dish soap works well. Or greased lightning. The GL works the best. Dry the part with cloths then compressed air (no pre-oiler in the supply) then prime.

If Im gonna blue the part with some oxphor Ill clean with GL, dry, then buff with a scotch bright pad to remove ALL loose partials. Then wash again and de-oil with MY favorite metal drying solvent, you can use acetone. For a part that I want to look nice Ill glass bead blast it before the oxphor with some wore out glass bead media.

But Im straying now cause anything that I want to look nice usually didnt start out with rust on it. Just needed some new bluing.

The only time I use the oxphor on old parts that had rust was with say an old lathe tool bit holder that was rusted. After removing the rust I want to protect the metal for future use and the oxphor does a good job. I have a gallon and it goes a LONG way. Not as durable as the original black oxide coating but much better than an oiling after its been stripped down. JR

Oh, one last thought. I have left parts in the evapo-rust for over a week and there is no harm done. UNLESS a section of the part is above the liquid. Big no-no!! It will rust big time. Worse than it was. Major pitting can occur if its in the air above the liquid. Some parts I just could not get below the surface so what I tried was taking three paper towels and layering them over the exposed sections. Making sure to saturate the paper towel then pressing it over the exposed part so all of the metal was layered with the towel and the towel was into to solution. So it can stay wet with wicking. Worked great. The part looked the same as the parts under the solution. After a week (too many projects, it didnt need to stay there that long) the "exposed" part was de-rusted. VS when I didnt wrap the part. Big time rusting :(

Fasttrack
06-15-2010, 10:29 PM
The dark or black color is simply carbon from the rusted steel... scrub it off with scotchbrite. If you want it "shiny", buff it with a non-abrasive.



Not likely. I suspect that is Iron (II) Oxide.

lazlo
06-15-2010, 10:53 PM
Not likely. I suspect that is Iron (II) Oxide.

EvapoRust is a chelating agent which binds the iron oxide into ferric sulfate.

lakeside53
06-15-2010, 10:55 PM
Evaporust says it's carbon from the steel - I called them.

Evaporust is brutal on the black oxides - put a degreased black oxide coated part in the solution, and it's stripped off in seconds.

lazlo
06-15-2010, 11:01 PM
http://i164.photobucket.com/albums/u15/rtgeorge_album/Evaporust.png


Evaporust is brutal on the black oxides - put a degreased black oxide coated part in the solution, and it's stripped off in seconds.

I've experienced the same -- it will strip black oxide right off.