TheSamba.com :: View topic

Tue Feb 04, 2020 6:58 am

So I have done a bunch of research and just looking for the best solution for my rust issue. On the hood of my 66 I have some rust that just will not come out even with an aggressive wire wheel. I tried to use Ospho but than did more research and found out that was a mistake. The epoxy lifts and fails from using Ospho. So I took it all off. Rinsed with water and acetone and blew it dry. Cutting out the rust is not an option for me in this case. I know it’s always best to remove it I know. I’m just looking to slow it down as best I can. The metal is in good shape where the left over rust is. My question is would it be ok to just spray a light coat of rust converter and shoot Omni mp 170 epoxy over it? Or I was thinking of just using some sort of vinegar treatment. I just don’t want the epoxy to fail. Yes I know this is not the correct way to go about it. Just looking for something that will play nice with the epoxy. Omni reps only want you to use there products

Tue Feb 04, 2020 8:42 am

I'm not a pro painter by any means, but I have done several paint jobs with excellent results using Duplicolor Rust Fix, and using epoxy or etching primer over the duplicolor. Body filler over the duplicolor seems okay too. Just need to make sure to follow the instructions and let it dry fully.

I would not recommend using that brown rusty metal primer rattle can. Personally, I've had poor results coating over that.

Tue Feb 04, 2020 10:27 am

I have had good luck with a product called Mastercoat. It's like por15 but better and a lot easier to paint over it.

Tue Feb 04, 2020 5:26 pm

It probably needs to be media blasted.

Tue Feb 04, 2020 6:09 pm

vwoldbug wrote: It probably needs to be media blasted. and if you have areas that can’t be blasted?

Wed Feb 05, 2020 12:02 am

Post some pictures of the rust.

Wed Feb 05, 2020 5:36 am

Try vinegar. You just need to get down to the root of the rust and get it out. The duplicolor rust fix works sometimes, and sometimes it doesn't for me. I don't know why. I would like to see a photo so I know what I am giving advice on....

Wed Feb 05, 2020 6:40 am

Any acid will remove rust or rather reduce oxidised iron to unoxidised iron. It just depends on how quickly you want to do this and the side reactions that will occur.

Vinegar is very weak acetic acid. You can use pool acid (HCl), sulfuric acid (H2SO4), citric acid or what we know as Ospho being phosphoric acid. Vinegar is a "weak" acid and takes a while whereas HCl, works very quickly but is dangerous if you are not careful. Some people swear by molasses, but I believe that the molasses just ferments to vinegar over time any way, so that is the active ingredient.

Some phosphoric acid based rust converters also have a polymer in it to help in preventing re-rusting or added zinc phosphate in it. This can leave a powdery or other deposit on the steel after use. This may be some of the problem that people are having with reactions with other coatings. If you can get just pure phosphoric acid,(available sometimes from cleaning companies dealing in the beverage or milk industries), you will only get iron phosphate as a by-product. Iron phosphate should be pretty inert to most coatings. Indeed if you use an etch primer, it will actually contain an acid (most likely phosphoric) to give that "etch".

Whatever you use, wash it thoroughly after use ( i mean well and truly-scrub it with a brush) let it dry and use a solvent like alcohol or acetone to remove any contamination which may remain. Do not wait before priming/painting etc. You must remove ALL the rust, otherwise you'll just waste your time.

Paints like POR15 still require you to use a acid based rust converter prior to painting.

Wed Feb 05, 2020 2:47 pm

TIMCO wrote: Post some pictures of the rust. heres some pics

Wed Feb 05, 2020 4:00 pm

Use a hamburger Patty stripping wheel. Then wire wheel. Then reverse the drill with the wire wheel. Then coat with mastercoat or epoxy primer. Let dry for a day. Lightly scratch it up with 80 grit. Do not break through. If you do cut through apply more mastercoat or epoxy. Red scuff pad then fill pits with filler. Its really not that bad .

Fri Feb 07, 2020 11:57 am

Sounds like a plan. Thanks

Fri Feb 07, 2020 1:32 pm

I you have a compressor, you can get those little spot blasters that would be ideal for this.

Sun Feb 09, 2020 10:31 am

Are you taking it all down to bare metal, or just selectively sanding the bad spots? I am stripping mine down to bare. Previous owner actually did not do that bad of a job, but I had to replace some rust areas that he tried to cover up, and I am changing the color anyway. Its the only way to find the spots he tried to hide. Looks similar to yours.

Fri Feb 14, 2020 11:07 pm

I asked an epoxy manufacturer about using metal prep then epoxy. He said to just clean it really well with preclean. If i used etching primer first to sand it off. Said if the epoxy chips the primer underneath can absorb moisture and rust under the epoxy.

Mon Mar 02, 2020 8:27 am

for very minor rust like shown in those pictures I have cleaned it up and wire brushed with Ospho over night. then cleaned the area again, sanding and wiping with acrylaclean or similar product.. spray it with some ONE STEP and prime over it after that.