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914World.com _ 914World Garage _ Metal Ready
Posted by: rjames Jan 25 2006, 04:41 PM
They guy at the local auto body shop said that metal ready wasn't necessary (probably because he was out of the stuff) before using POR15 as long as I did a good job of grinding all of the rust out.
This doesn't sound correct as I'll never be able to grind and clean up ALL of the rust particles...
However, I've seen the instructions for the Metal Ready stuff, and it sounds like a big mess. Is there another product that's less messier that will do the same thing (assuming I need it)? Rubbing alcohol? (at least that stuff will evaporate on it's own).
Also, I've got areas where I won't be able to wash the metal ready stuff out of if I apply it (center tunnel comes to mind). I can't just spray Metal Ready in there because it's an acid and eventually will destroy the metal- I have to be able to wash the stuff out. So do I just try and coat with POR15 using some sort of 'rag-on-a-pole' method??
New pics of the longs, rust etc:
http://www.914world.com/bbs2/index.php?act=ST&f=2&t=44837&hl=metal+ready
Since I have a couple of small areas to weld later, can I grind of the POR15 easily (or easily enough) when the time comes to weld those areas? (ie: holes due to rust)
Posted by: bondo Jan 25 2006, 04:44 PM
Jasco metal etch is pretty similar and much cheaper. Still messy.
Posted by: airsix Jan 25 2006, 04:50 PM
Messy but effective. Don't take shortcuts IMHO.
Posted by: Rand Jan 25 2006, 04:51 PM
According to the company, POR15 is "designed for application directly on rusted or seasoned metal."
Metal ready is for etching slick metal "including aluminum and shiny polished metal surfaces" for better adhesion.
http://www.por15.com/PRODUCTS/PRIMERPAINTSCOATINGS/POR15RUSTPREVENTIVEPAINT/POR15/tabid/139/Default.aspx
http://www.por15.com/PRODUCTS/CLEANERSDEGREASERS/METALREADY/tabid/80/Default.aspx
I heard a guy recommend letting the surface rust on new sheet metal before painting with POR15 so it would adhere better. 
I would use Metal Ready instead, but you are supposed to be able to just wire brush the loose rust off and paint with POR15 - nothing else required.
Personally, I like http://www.kilz.com/pages/default.aspx?NavID=42 and http://www.kilz.com/pages/default.aspx?NavID=42.
Posted by: tat2dphreak Jan 25 2006, 04:54 PM
if you are using real POR-15, use Metal ready too... otherwise, Ospho is cheaper, and easier and acts as a primer
Posted by: rjames Jan 25 2006, 04:57 PM
I'm leaning towards some kind of rust inhibitor product.
I just don't want to mess this up now that I've come this far.
I guess the plan after getting down to the bare metal
is to
1) degrease
2) ospho/metal ready/jasco (some type of rust inhibitor
3) Por15
Still not sure about the areas like the center channel I can't get into enough to completely clean out any rust inhibitor I spray in there though.
Posted by: Bartlett 914 Jan 25 2006, 05:00 PM
I can't say for sure if you need metal ready or not. I haven't used this or any other product as yet. I have done a little reading and asking about this and other products.
I have heard that Por 15 sometimes does not stick properly to bare metal. It sticks very well to rust. This product and others that are similar work by absorbing moisture. The material fills all the small cracks and pores in the rust. The moisture is absorbed in the Por 15 in the curing process. This prevents the rust from spreading. I read in another pose a recomendation of using Ospho or something else before Por 15. I think this is a mistake. There are other products like Ospho that changes the rust to something else. These materials turn black on contact with the metal. I would be cocerned this may cause some adverse reaction. I also would not use alchol or any solvent in the cleaning. At least you should finish with a water base cleaner. I believe this is spelled out in the manufactures instructions.
I purchased another product called Rust Bullet. Haven't used it yet. I have heard it is a good product. Do a google and decide for yourself.
Lots of luck on your car. It look a lot better than my project!
Mark
Posted by: TimT Jan 25 2006, 05:02 PM
Use white vinegar 
Posted by: lapuwali Jan 25 2006, 05:34 PM
There are some who would say the opposite: use Metal Ready (or equivalent) and DON'T use POR-15.
If you use anything with phosphoric acid (Metal Ready, Ospho, Navel Jelly, etc) in it, you're converting the rust from iron oxide to iron phosphate, which won't rust any furthur, and the phosphate ions occupy all of the space the oxygen ions are trying to attach themselves to. POR-15, et al, will "seal" the metal so more oxygen atoms can't get to the iron atoms, so rust is stopped.
My take is to use both. Metal Ready over rusty metal will halt the rust that's forming now, and it gives you a better surface for the POR to stick to. It also etches the metal that's not rusty, which also increases the chances of the POR sticking to that. The Metal Ready doesn't do much to protect steel that's not already rusted, which the POR will do.
Ospho only converts, it doesn't etch. I think Jasco will do both.
Posted by: Eric_Shea Jan 25 2006, 06:01 PM
Never used it (Metal Ready). I've only applied POR-15 to bead blasted clean metal.
I use Zero-Rust now for most applications now.
Posted by: SirAndy Jan 25 2006, 06:44 PM
| QUOTE (lapuwali @ Jan 25 2006, 03:34 PM) |
| If you use anything with phosphoric acid (Metal Ready, Ospho, Navel Jelly, etc) in it, you're converting the rust from iron oxide to iron phosphate, which won't rust any furthur, and the phosphate ions occupy all of the space the oxygen ions are trying to attach themselves to. POR-15, et al, will "seal" the metal so more oxygen atoms can't get to the iron atoms, so rust is stopped. |
POR-15 alone does not do anything to or with the rust. it just seals the surface so no more moisture or oxygen can get to it.if the POR-15 coat is compromised, you got a nice moisture trap between the POR-15 and the *bare* metal you covered with it ...
metal ready on the other hand chemically reacts with the rust (even bare metal to a certain degree) and stops rust dead on.
i always metal-ready any surface, like for example after welding. let it dry. if you used too much, wipe it off with a wet cloth.
when dry, paint it with your favorite primer/paint or put a top-coat of POR-15 over it.
i have seen POR-15 applied directly to rusted surfaces and it'll hold up for a while, but if the rust underneath is too much, it'll eventually bubble and break through ...
Andy
Posted by: McMark Jan 25 2006, 06:48 PM
Metal Ready leaves a zinc layer as well.
Posted by: Rrrockhound Jan 25 2006, 06:50 PM
| QUOTE |
| i have seen POR-15 applied directly to rusted surfaces and it'll hold up for a while, but if the rust underneath is too much, it'll eventually bubble and break through ... |
The PO had POR-15'd the battery tray on my teener, which is now peeling like crazy, as if he didn't prep it properly first. Still pretty solid tho, but that's one thing to do on my warm weather list.
Posted by: Rand Jan 25 2006, 06:56 PM
| QUOTE (Rrrockhound @ Jan 25 2006, 04:50 PM) | ||
The PO had POR-15'd the battery tray on my teener, which is now peeling like crazy, as if he didn't prep it properly first. Still pretty solid tho, but that's one thing to do on my warm weather list. |
You can only put POR15 (or any other rust-"encapsulating" paint) over surface rust on good base metal. If there are scales, or the rust can come through the back side, that's another matter - which means the rot needs to be cut out and replaced with good metal.
Posted by: rjames Jan 25 2006, 06:58 PM
Hmm ok, so I will go find some metal ready. What about the areas that I can't rinse the metal ready off very well? Like the center chanel? Or the enclosed area to the left of the pedal cluster (accessible by only a 50cent piece size hole)? Or in the jack area on the rocker panel?
Sorry for all the questions, and the bad pics (see below)
Attached image(s)
Posted by: rjames Jan 25 2006, 06:59 PM
ads
Attached image(s)
Posted by: Rand Jan 25 2006, 07:04 PM
| QUOTE (rjames @ Jan 25 2006, 04:58 PM) |
| Hmm ok, so I will go find some metal ready. What about the areas that I can't rinse the metal ready off very well? Like the center chanel? Or the enclosed area to the left of the pedal cluster (accessible by only a 50cent piece size hole)? Or in the jack area on the rocker panel? Sorry for all the questions, and the bad pics (see below) |
Center tunnel: It's surface rust... do your best to brush and vacuum it out. Paint it with Hammerite or POR15. Period. No Metal Ready needed.
Jack plate: Cut it off. Cut rotted metal out around that area back far enough to get rid of rotted metal and into good metal. Weld in new sheet metal. Metal Ready the new metal if you like (or sand it to get a non-slick surface). Paint the area well. Perhaps with POR15 or Hammerite.
My $.02, and I know it will work for at least 30 years. Or so, depending on environment.
Posted by: rjames Jan 25 2006, 07:08 PM
Your 2 cents is welcomed! Seriously!
| QUOTE |
| Jack plate: Cut it off. Cut rotted metal out around that area back far enough to get rid of rotted metal and into good metal. Weld in new sheet metal. |
Do I really need the jack plate? I was thinking about cutting it out and leaving it off.
Posted by: sgomes Jan 25 2006, 07:17 PM
Let me jump in here too. I'm about to dig into this:
My plan was to cut away a hole big enough to get inside the long and do what I can Metal Ready and POR-15wise...
If I have to wash the Metal Ready after application...then I may not want to do that!
What have others done inside the long or as the OP asked, inside the tunnel?
Posted by: SirAndy Jan 25 2006, 07:21 PM
| QUOTE (rjames @ Jan 25 2006, 04:58 PM) |
| What about the areas that I can't rinse the metal ready off very well? Like the center chanel? |
i sprayed the hell out of my center tunnel and longs. took 2 days for the metal ready to dry. no need to wash anything off, unless you plan on painting it inside and leave it exposed for everyone to admire the inside of your center tunnel ...
excess MR won't hurt anything, it's just hard to primer over. you only have to wash it off if you want to primer and paint that area. that's why you should wash it down if you applied it to thick ...
Andy
Posted by: Rand Jan 25 2006, 07:25 PM
| QUOTE |
| Do I really need the jack plate? I was thinking about cutting it out and leaving it off. |
You don't need the jack plate. Just get a good scissor jack.
I was reluctant to remove mine at first.... it's nice to stick a factory jack in there and lift the whole side of the car. When I asked why it was bad, people told me stories about their car rolling forward and ripping the jack plate out... I thought - dumb, that had to be a severely rotted plate, and why wasn't it e-braked and blocked? But in my rust repair efforts, it was easier to just delete and clean. Make it simple and strong. A standard scissors jack is fine and more versatile.
Posted by: sgomes Jan 26 2006, 12:14 AM
| QUOTE | ||
i sprayed the hell out of my center tunnel and longs. took 2 days for the metal ready to dry. no need to wash anything off, unless you plan on painting it inside Andy |
When you say "unless you plan on painting" are you including POR-15?
How did you spray the MR inside there?
Posted by: Rand Jan 26 2006, 01:09 AM
I don't see the point of trying to spray Metal Ready inside the longs. I guess we'll get different opinions on this, but... Metal Ready is for etching. The inside of your longs don't need that. If you're gonna spray something in there, use something that will encapsulate the rust (kill it) and stop it from spreading.... Such as Hammerite or POR 15.
Posted by: sgomes Jan 26 2006, 08:22 AM
| QUOTE (SirAndy @ Jan 25 2006, 04:44 PM) |
| POR-15 alone does not do anything to or with the rust. it just seals the surface so no more moisture or oxygen can get to it. if the POR-15 coat is compromised, you got a nice moisture trap between the POR-15 and the *bare* metal you covered with it ... metal ready on the other hand chemically reacts with the rust (even bare metal to a certain degree) and stops rust dead on. Andy |
What he said...
And MR supposedly leaves behind a layer of zinc.... something these cars should have had from the start!
Posted by: Vacca Rabite Jan 26 2006, 08:32 AM
| QUOTE (SirAndy @ Jan 25 2006, 08:21 PM) | ||
i sprayed the hell out of my center tunnel and longs. took 2 days for the metal ready to dry. no need to wash anything off, unless you plan on painting it inside and leave it exposed for everyone to admire the inside of your center tunnel ... excess MR won't hurt anything, it's just hard to primer over. you only have to wash it off if you want to primer and paint that area. that's why you should wash it down if you applied it to thick ... Andy |
This is what I did as well. When I cut the bad metal out of my longs, I sprayed the insides with a ton of metal ready, and let it get a good zinc coating. I've not doen that to the center tunnel yet, due to me not wanting to harm the wire harness still in it.
Basically, anywhere I saw a bit of rust that was small, but too concealed to cut into, I sprayed down with a ton of metal ready.
Zach
Posted by: maf914 Jan 26 2006, 09:40 AM
| QUOTE (sgomes @ Jan 25 2006, 10:14 PM) |
| How did you spray the MR inside there? |
You can spray chemicals using a garden insecticide sprayer, the type with a 2 to 3 gallon plastic bottle with attached air pump. The spray wand can be inserted into hard to reach spots with the nozzle adjusted to give a wide spray pattern. They are cheap, $20 or so, at Wally World, K-Mart, Homa-da-Pot, etc.
Posted by: SirAndy Jan 26 2006, 01:18 PM
| QUOTE (sgomes @ Jan 25 2006, 10:14 PM) |
| When you say "unless you plan on painting" are you including POR-15? How did you spray the MR inside there? |
depends ... you can brush/spray POR over MR, but if the MR layer is too thick, you'll need to scuff it for the POR to stick right. if you don't do that, the POR will still make a good seal, but it will not stick well to the MR. i have been able to peel of POR in big chunks from a piece of trunk that had too much MR on it ...
i don't think it would be a problem in the center tunnel, but then again, i did not use any POR inside the center tunnel at all ...
bottomline, if you're gonna put something on top of a thick layer of MR, you have to prep the MR surface first to get some "stick".
just like you would prep any other surface for paint ...
i just use a spray bottle with a small hose extension ...
Andy
Posted by: SirAndy Jan 26 2006, 01:20 PM
| QUOTE (Rand @ Jan 25 2006, 11:09 PM) |
| I don't see the point of trying to spray Metal Ready inside the longs. I guess we'll get different opinions on this, but... Metal Ready is for etching. The inside of your longs don't need that. If you're gonna spray something in there, use something that will encapsulate the rust (kill it) and stop it from spreading.... Such as Hammerite or POR 15. |
POR 15 does not kill rust. no chemical bond with the rust. MR on the other hand does ...
it's not a "etching" primer. it's a "rust-converter". POR is not. it's just to seal a surface. any rust "under" a layer of POR will still be just that, rust on your car. if it's big enough of a bubble, it will continue to eat through your car.
POR does not kill rust ...
Andy
Posted by: Rand Jan 26 2006, 01:46 PM
I'm with you Andy - not arguing... But it seems like they are saying Metal Ready isn't necessary and POR15 will permanently stop the rust...
| QUOTE |
| POR-15® is a high-tech, high performance rust-preventive coating designed for application directly on rusted or seasoned metal surfaces. It dries to an incredible rock-hard, non-porous finish that won't chip, crack, or peel, and it prevents rust from recurring by protecting metal from further exposure to moisture. Use POR-15® to coat rusty frames, floor pans, farm equipment, marine equipment, or even a heavily corroded battery tray. |
| QUOTE |
| METAL-READY™ provides the best adhesion for POR-15® on any surface, including aluminum and shiny polished metal surfaces. Our simple process gently etches metal, creating an ideal anchor pattern for coatings such as POR-15® |
For sure anything loose needs to be wirebrushed off and thick rust should be cut out before any other treatment.
Posted by: SirAndy Jan 26 2006, 02:16 PM
| QUOTE (Rand @ Jan 26 2006, 11:46 AM) |
| I'm with you Andy - not arguing... |
i wasn't either ...
i've read their "sales" pitch.
what i posted are results from my own 4+ years of experience with both products as well as other peoples experience during that time.
so far, the best results have been by using both products combined, metal ready to eliminate surface rust and give the metal a protective zinc layer, then por15 to seal the surface completely.
i did the complete interior of my car that way 3 years ago and i have had numerous "flooding" incidents since then (car is parked outside).
plenty of standing water on my floorboards, but the por15 has been holding up nicely.
no bubbling from underneath either.
so, it's working for me ...
Andy
Posted by: Rand Jan 26 2006, 02:33 PM
Nothing like real-world proof. Gotta go with what is known to work!
So has anyone used POR15 without Metal Ready on a rusty surface that was cleaned up (no loose or thick rust) and have results to share?
Posted by: rjames Jan 26 2006, 02:38 PM
What about the Marine Clean degreaser stuff they sell that they say to use before Metal Ready? yikes, it never ends....
My concern with leaving Metal Ready on without washing it off (depending on how much you use I guess) is that it will 'continue' to etch into the metal. What is this etching process? At what point does it stop? I guess when it's washed off, or evaporates, which would lead me to believe you wouldn't want to saturate an area with the stuff and just leave it to evaporate- especially if it's going to take a couple of days or more to do so. 
Posted by: SirAndy Jan 26 2006, 02:57 PM
| QUOTE (Rand @ Jan 26 2006, 12:33 PM) |
| So has anyone used POR15 without Metal Ready on a rusty surface that was cleaned up (no loose or thick rust) and have results to share? |
yes!
worked for maybe a year or so before the rust started to bubble up again and eventually the por15 could be just peeled off in chunks with the rust still sticking to it in the back.
that was on a rusty battery tray that had the loose rust stuff cleaned off and then simply por15-ed over with two coats.
Andy
Posted by: SirAndy Jan 26 2006, 03:00 PM
| QUOTE (rjames @ Jan 26 2006, 12:38 PM) |
| My concern with leaving Metal Ready on without washing it off (depending on how much you use I guess) is that it will 'continue' to etch into the metal. What is this etching process? At what point does it stop? I guess when it's washed off, or evaporates, which would lead me to believe you wouldn't want to saturate an area with the stuff and just leave it to evaporate- especially if it's going to take a couple of days or more to do so. |
very good question ...
i can't check on my longs as they're welded shut now, but i can check on my center tunnel as it got the "hurt me plenty" Metal Ready treatment ...
i'll go and check tonight or tomorrow and see if i can see any unusual "pitting" of the surface ...
Andy
Posted by: Rand Jan 26 2006, 03:11 PM
I know Ospho does not continue eating metal. After 24 hours, once it's dry, it's done. I wouldn't think Metal Ready could continue acting once it's dry either. To continue acting, it would have to be "fed." Unfortunately, rust is fed by moisture - but I don't think anything in the atmosphere feeds MR. I don't have experience with MR though.
Good stuff! Thanks Andy!
Posted by: rjames Jan 26 2006, 03:58 PM
Yes, big thanks to all who are contributing to this discussion! 
I just want to make sure I do this right (seeing as I only want to do this once!)
| QUOTE |
| i can't check on my longs as they're welded shut now, but i can check on my center tunnel as it got the "hurt me plenty" Metal Ready treatment ... |
Looking forward to what you find Andy!
On related topic...
On my car since there is rust at the top of the outside of the longs (running the entire length of the longs) and rust inside the passenger compartment at the floor level (where the outer and inner meet, I guess) I can probably assume that there is surface rust at the very least within the longs. Do I want to cut into them to try and treat it? Or just treat the outside surfaces and check periodically? Wow. Way too many questions.
(see below for pic regarding this scenario. Arrow points to a hole, but you can see that rust runs the length at the top. I can't poke through it with a screwdriver, but probably will be able to eventually...
)
Attached image(s)
Posted by: SirAndy Jan 26 2006, 04:05 PM
| QUOTE (rjames @ Jan 26 2006, 01:58 PM) |
| Do I want to cut into them to try and treat it? Or just treat the outside surfaces and check periodically? |
well, my longs alreay had a "access hole", right under the battery tray.
so i didn't really have to cut them open much.
you can, however, access the longs (partially) by using the oval holes on the inside (cabin).
they're patched with a piece of tar, when removed you'll see the heater muffler.
you can spray MR in there through those holes ...
on the outside, clean up any lose stuff, make sure it's not rusted through (in which case you should
) then spray MR onto the surface rust ... Andy
Posted by: sgomes Jan 26 2006, 04:09 PM
| QUOTE |
| I know Ospho does not continue eating metal. After 24 hours, once it's dry, it's done. I wouldn't think Metal Ready could continue acting once it's dry either. To continue acting, it would have to be "fed." Unfortunately, rust is fed by moisture - but I don't think anything in the atmosphere feeds MR. I don't have experience with MR though. |
I'm with you on that. It's a chemical reaction. Once it "reacts" it won't "act" anymore. As I understand it, it's a rust converter. So once the reaction has gone to completion...that's it! Now if you put GALLONS of it on there....the ratio of MetalReady to Metal might not be in your favor. It might continue to etch for quite some time...even after it's dry.
Posted by: Rrrockhound Jan 26 2006, 06:36 PM
| QUOTE (sgomes @ Jan 26 2006, 05:09 PM) | ||
I'm with you on that. It's a chemical reaction. Once it "reacts" it won't "act" anymore. As I understand it, it's a rust converter. So once the reaction has gone to completion...that's it! Now if you put GALLONS of it on there....the ratio of MetalReady to Metal might not be in your favor. It might continue to etch for quite some time...even after it's dry. |
Metal Ready is phosphoric acid. Phosphoric is a weak acid, weaker than battery acid, but stronger than acetic (vinegar). They also use it to flavor soda. Anyway, it will only react until it uses up the phosphate (creating iron phosphate, a common conversion coating). It won't just keep etching and etching. I doubt POR-15 would jeopardize their business by making a super-concentrated Metal Ready that would eat up your car.
Posted by: kwales Jan 26 2006, 07:32 PM
I remove all loose rust, clean the surface well and then use ospho to initially treat the rust. Unprotected, the rust will start again.
Next you have to cover the unprotected metal with something. Everybody seems to like POR 15 but it didn't pass my test of 2 coats on a steel strip, dunk the sucker into salty water for 2 weeks. I wanted something better.
With thatin mind, I opened my long, used a wire brush and a sand blaster to remove rust, applied ospho, and then sprayed a REELLLY thick bunch of layers of cold galvanize paint in there. The cold galvanize is 95% ground zinc (sacrificial anode) and 5% binder. Salt test showed it is porous soooooo......
Kenny sealed off it with a buncha layers of cavity wax (like cosmoline with rust inhibitors). A British car mag ran rust tests and the Dinotrol cavity waxes provided the absolute best rust protection bar none, sealed scrapes and bumps, and actually protected the metal on the other side and about an inch away from the coating...
SO I got neutralized rust, sacrificial zinc and then this cavity wax...
Bet I don't have to go in there again....
Ken
Posted by: swl Jan 26 2006, 07:55 PM
I can't resist wading in here and risking the flames but what the heck. Boy scientist mode engaged.
Let's go back to basic. Rust doesn't cause rust. Iron molecules exposed to oxygen molecules cause rust. Period. Any (well most) rust prevention simply aims at keeping the oxygen away from the iron. How well it does that job depends on how effective it is at getting to the iron and sticking to it. The sales pitch for POR and it's competitors is two fold. One it can penetrate surface rust and find it's way to the underlying metal. Two, the coating is very flexible to prevent cracking yet strong enough to resist abrasion.
Put up your hands if you have ever seen aluminum rust. See all the college boys are going nuts. Aluminum rusts much more easily than iron. Difference is that the size of an molecule of aluminum oxide is exactly the same as the normal aluminum molecule. As a result the aluminum oxide forms a barier to the oxygen trying to get at more aluminum. The 'rust' layer is very very thin so it just looks like there is no rust. With iron however the rust molecule is much larger than the iron molecule. This causes the bubbling, flaking and cracking that we all are so familiar with. This winds up exposing more iron to the oxygen and the rust grows and grows.
I don't know much about phosphate chemistry but by observation the metal ready is transforming the iron oxide into something that is much more powdery and can be easily swept away. It may also be forming a layer like the aluminum does to keep oyxgen away from the iron. Andy has seen this by the protection resulting from just a metal ready application. I would suggest that the protective layer is probably very fragile and you would not want to rely on it alone anywhere that gets any sort of abrasion.
My philosophy. If you are going to buy into someone's chemistry buy in all the way. Unless they are a complete bunch of con artists they have invested a lot of work to come up with the process. Marine clean removes any oil/grease/gunk that would stop the POR from getting to or bonding to the metal. Gross rust has to be removed with a wire brush. Metal ready further reduces the standing rust to give the POR a chance to get to the metal. But again read the instructions - they want you to rinse off the debris. Last step is the POR itself. Like any other paint job it is all about the prep work. Yeah, POR is making a killing off us. But, man, you don't want to ever have to do it again!
Boy scientist mode disengaged.
Posted by: SirAndy Jan 26 2006, 08:04 PM
| QUOTE (swl @ Jan 26 2006, 05:55 PM) |
| Let's go back to basic. Rust doesn't cause rust. Iron molecules exposed to oxygen molecules cause rust. Period. |
well, actually ....
http://antoine.frostburg.edu/chem/senese/101/redox/faq/how-iron-rusts.shtml
Andy
Posted by: swl Jan 26 2006, 08:20 PM
ouch andy - my brain dumped all that complex intermediate stuff after the exam. I just like the bottom line fe2o2 everything before that is jfm. yeah - the reaction only progresses in the presence of water and an electrolite to conduct the electrons. Point for the discussion though is that only involvement of existing rust is to prevent the coating from reaching the iron.
Posted by: rjames Jan 26 2006, 08:48 PM
Wow, excellent discussion folks. I personally think someone should
tip the makers of POR-15 off to this thread so they can provide
free samples for us to experiement with....that stuff aint cheap!
Currently I'm leaning towards their full process....marine clean, metal ready, then POR-15 in black (matches the exterior!)
Posted by: sgomes Jan 26 2006, 10:14 PM
I followed this high school chemistry class right up until Steve said that the Iron Oxide is converted into something more powdery to be swept away.
My experience with Navel Jelly (which I believe to be the same kind of converter...I could be wrong here) is that it converts it to this black stuff that I couldn't get off the metal to save my life! It didn't seem to "powdery".
This is a key point. Since POR-15 wants you to use MR underneath, wouldn't this be a bad idea?? Yeah I know they want you to wash it off but who here believes they could wash it well enough to remove it all? My bet is that stuff is attached on there with a vengence and the washing idea is to remove the "unreacted" MR off so that the POR-15 can cling to the metal directly.
Should I go back to high school? 
Posted by: SirAndy Jan 27 2006, 12:33 AM
| QUOTE (sgomes @ Jan 26 2006, 08:14 PM) |
| My bet is that stuff is attached on there with a vengence and the washing idea is to remove the "unreacted" MR off so that the POR-15 can cling to the metal directly. |
Posted by: kwales Jan 27 2006, 09:36 AM
Shannon, the hard black stuff is magnetite or converted rust.
Rust is an electrical process. It forms charged cells. The attached picture on the left shows a cross section of a rust cell. The bulge at the top is what we see. Below it is a deep tapering pit of rust. When you sandblast, the sand particles penetrate as deep as they can into the pit but can't reach the narrow bottom......
On the right is an ospho or metal ready treated rust cell. The cell has been wire brushed to knock off the bulge, and then treated. The surface of the remaining rust cell is converted to magnetie, a hard stable form of iron oxide. How deep the treatment is, I can't say. But I do know from sandblasting, you can find rust underneath.
The magnetite is a seal to prevent oxygen from reaching the metal below. The rust cell is still there, still wants to rust but is blocked. The POR or other paint acts as a shield to prevent the treated rust from getting the 2 things it needs- water and oxygen.
Posted by: kwales Jan 27 2006, 09:38 AM
Ooops, forgot the picture....
Attached image(s)
Posted by: sgomes Jan 27 2006, 09:51 AM
I think I can speak for everyone,
This thread rocks!
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