Rust Removal with Molassas


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Post Sat Feb 16, 2013 11:07 am

Rust Removal with Molassas

I found out you can remove rust by soaking the part in a vat of 9 parts water and 1 part molassas (the kind with sulfuric acid in it - at grain feed places etc ). I've done 3 batches - got most of the parts of my truck except the cab itself.(Fenders, grill, hood, connecting pieces etc) The rust comes off easily with a spray washer when you remove it from the vat. Questions:
1) all the pitted metal (mostly underside of fenders and hood ) - do you just prime it and fill it or fill it with body filler first and then prime it - or just prime it and not fill it cuz its not visible? I know that's up to me but I am curious as to the 'norm'. One local body shop told me there are primers that are thicker and have some polysomething or the other in them and use that first?
2) Is there a good guide or previous discussion on body work - I have a couple of 2 inch diameter holes, one 3 to 4 inch piece missing and a couple of cracks in the metal.
3) POR 15 is supposed to be good on areas where I can get away with just stopping the rust (Converting type Paint). I found some cheaper converting type paint called Rust Converter - am I better off going with the POR 15 expensive stuff?
4)There are so many dents on this thing I think it was used by a demolition company that was slopy with the front end loader and dropped stuff all over the truck! Would you recommend hammering out the dents or filling them? Some are an inch or two deep.
Rocky (I have a 41 K5).

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Post Sat Feb 16, 2013 11:48 am

Re: Rust Removal with Molassas

Rocky wrote:I found out you can remove rust by soaking the part in a vat of 9 parts water and 1 part molassas (the kind with sulfuric acid in it - at grain feed places etc ). I've done 3 batches - got most of the parts of my truck except the cab itself.(Fenders, grill, hood, connecting pieces etc) The rust comes off easily with a spray washer when you remove it from the vat. Questions:
1) all the pitted metal (mostly underside of fenders and hood ) - do you just prime it and fill it or fill it with body filler first and then prime it - or just prime it and not fill it cuz its not visible? I know that's up to me but I am curious as to the 'norm'. One local body shop told me there are primers that are thicker and have some polysomething or the other in them and use that first?
2) Is there a good guide or previous discussion on body work - I have a couple of 2 inch diameter holes, one 3 to 4 inch piece missing and a couple of cracks in the metal.
3) POR 15 is supposed to be good on areas where I can get away with just stopping the rust (Converting type Paint). I found some cheaper converting type paint called Rust Converter - am I better off going with the POR 15 expensive stuff?
4)There are so many dents on this thing I think it was used by a demolition company that was slopy with the front end loader and dropped stuff all over the truck! Would you recommend hammering out the dents or filling them? Some are an inch or two deep.
Rocky (I have a 41 K5).

If you can, fill with a good self leveling primer(one that will work with your top coats). Holes/rips, if you are good at welding, fill them with a patch piece, then finish out like any other body work. Big dents, much better off to "work" them out so there is not much "fill" material, Do not care how good it is, most fillers will eventually come out.(my opinion) Work your dents with a rubber bag filled with sand, and a wooden mallets/tools, takes more time, but will not distort the metal as much. You can work the Big stuff with other hammers to get to the basic shape. Other option, look for a better Cab/fenders.
lloyd

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Post Sun Feb 17, 2013 2:00 pm

Re: Rust Removal with Molassas

I have used electrolytic rust removal with pretty good results. Here's a link to a page with good info:
http://www.instructables.com/id/Electro ... aka-Magic/

Takes it down to bare metal like a charm, but subject to flash rusting. Living in the desert helps. So does baking parts in the oven afterward to dry them out. (Ssssh- don't tell the wife ;) )

I have used 2 types of rust converting paint. Duplicolor makes a clear coat that works pretty good, it turns the rust purplish. It doesn't spray real well- kind of like skillet spray- and requires sanding afterwards, but does the job. Rustoleum makes a rust converting paint that sprays better and costs about half as much. Unsure how good a job it does at rust conversion, though. Just looks like black primer. We'll see if the rust comes back.

I derusted my brake drums, but didn't use any rust converting paint because it doesn't like high temps and the rust is starting to come back already. Might try the POR15 there.
"How the heck did that happen?"

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Post Mon Feb 18, 2013 9:30 am

Re: Rust Removal with Molassas

lbesq wrote:
Rocky wrote:I found out you can remove rust by soaking the part in a vat of 9 parts water and 1 part molassas (the kind with sulfuric acid in it - at grain feed places etc ). I've done 3 batches - got most of the parts of my truck except the cab itself.(Fenders, grill, hood, connecting pieces etc) The rust comes off easily with a spray washer when you remove it from the vat. Questions:
1) all the pitted metal (mostly underside of fenders and hood ) - do you just prime it and fill it or fill it with body filler first and then prime it - or just prime it and not fill it cuz its not visible? I know that's up to me but I am curious as to the 'norm'. One local body shop told me there are primers that are thicker and have some polysomething or the other in them and use that first?
2) Is there a good guide or previous discussion on body work - I have a couple of 2 inch diameter holes, one 3 to 4 inch piece missing and a couple of cracks in the metal.
3) POR 15 is supposed to be good on areas where I can get away with just stopping the rust (Converting type Paint). I found some cheaper converting type paint called Rust Converter - am I better off going with the POR 15 expensive stuff?
4)There are so many dents on this thing I think it was used by a demolition company that was slopy with the front end loader and dropped stuff all over the truck! Would you recommend hammering out the dents or filling them? Some are an inch or two deep.
Rocky (I have a 41 K5).

If you can, fill with a good self leveling primer(one that will work with your top coats). Holes/rips, if you are good at welding, fill them with a patch piece, then finish out like any other body work. Big dents, much better off to "work" them out so there is not much "fill" material, Do not care how good it is, most fillers will eventually come out.(my opinion) Work your dents with a rubber bag filled with sand, and a wooden mallets/tools, takes more time, but will not distort the metal as much. You can work the Big stuff with other hammers to get to the basic shape. Other option, look for a better Cab/fenders.
lloyd

Thanks lloyd!

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Post Mon Feb 18, 2013 9:33 am

Re: Rust Removal with Molassas

OhioBoy wrote:I have used electrolytic rust removal with pretty good results. Here's a link to a page with good info:
http://www.instructables.com/id/Electro ... aka-Magic/

Takes it down to bare metal like a charm, but subject to flash rusting. Living in the desert helps. So does baking parts in the oven afterward to dry them out. (Ssssh- don't tell the wife ;) )

I have used 2 types of rust converting paint. Duplicolor makes a clear coat that works pretty good, it turns the rust purplish. It doesn't spray real well- kind of like skillet spray- and requires sanding afterwards, but does the job. Rustoleum makes a rust converting paint that sprays better and costs about half as much. Unsure how good a job it does at rust conversion, though. Just looks like black primer. We'll see if the rust comes back.

I derusted my brake drums, but didn't use any rust converting paint because it doesn't like high temps and the rust is starting to come back already. Might try the POR15 there.

Thanks! Love that oven tip!

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Post Tue Feb 19, 2013 2:03 pm

Re: Rust Removal with Molassas

By the way, not only is there a big difference in price, but there is a big difference between a rust converter and POR-15. Rust converter I think does actually neutralize the rust that exists but doesn't prevent any rust from coming back. POR-15 encapsulates the rust and steel to keep oxygen out and will effectively stop rust from forming (no oxygen = no rust). Its a very hard and tough coating, but if you sand down to bare metal you break the coating and can get rust again. I'm not saying one is better than the other, but they are definitely different.
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Post Wed Feb 20, 2013 1:21 pm

Re: Rust Removal with Molassas

any time you use rust converter, you do have to paint with something. Left alone for long, rust will reappear if you do not treat the rust converter covered area and paint.

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