Metal Ready, necessary? |
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Metal Ready, necessary? |
rjames |
Jan 25 2006, 04:41 PM
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#1
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I'm made of metal Group: Members Posts: 4,111 Joined: 24-July 05 From: Shoreline, WA Member No.: 4,467 Region Association: Pacific Northwest |
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=...&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) |
swl |
Jan 26 2006, 07:55 PM
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#2
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Senior Member Group: Members Posts: 1,409 Joined: 7-August 05 From: Kingston,On,Canada Member No.: 4,550 Region Association: Canada |
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. |
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