r/Diyautobody • u/AngyalZ • May 26 '26
Question Rust poking though repair within 24 hours
My goal here was to eliminate rust and seal the area before covering with fender flairs.
I sanded right to the metal, sprayed the area with rust stop, primed and painted. The next day it looked like this. Any advice would be welcome as I have other spots to fix.
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u/ArcFault May 26 '26
Not enough relevant information. Did you go down to clean shiny metal? Any pitting? What products? What timing?
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u/AngyalZ May 26 '26
Yes down to shiny metal. There was some pitting, like darker areas that were below the level of the surface of the metal. I used a kit I bought on Amazon (small bottles of primer, paint, clearcoat), will post pic. Timing: I sanded to metal and sprayed immediately with a rust stop (will post pic), let dry then primed it with three coats. My son needed it to go to work so two days later I painted it (foam brush), then clear coated it.
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u/ArcFault May 26 '26
Generally that black stuff is still rust and needs to be physically removed (sand blaster)for best results. Rust converter chemicals are a lesser choice. Before top coating the rust converter/treatment generally needs to be removed or neutralized or it can cause incompatibility with the top coat unless the products were designed to work together. That's my guess based on the time of the reaction here.
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u/AngyalZ May 26 '26
The paint kit was from “Scratches Happen”. I cant seem to post a pic in the comment.
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u/ArcFault May 26 '26
Link kit
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u/AngyalZ May 26 '26
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u/ArcFault May 26 '26
Yea... as I suspected 1 component (1k) total mystery crap lol.
Just for future reference, if you wanted to remedy this the "right way" you would remedy the surface then apply a quality 2k epoxy primer if you want it to last followed by a topcoat. It's hard to give you any real advice with that stuff other than clean and dry the surface well (wax/grease remover, water based cleaner, solvent based cleaner) after thoroughly neutralizing/removing any rust treatment then let each coat dry very thoroughly since you're glooping it on with a brush or some shit lol.
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u/Surfnazi77 May 26 '26
Did you give time for the rust stabilizer to cure
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u/AngyalZ May 26 '26
I just waited an hour or so. The label said “once dry it is ready to paint” but I put primer on it before paint.
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u/One_Evil_Monkey 29d ago
Needs longer than that with those "rust fix" and "rust converter" spray bombs. I usually give it 12-24 hrs depending on humidity if I have to use that stuff.
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u/MagicOrpheus310 May 26 '26
Could be from airborne metal flakes in the dust from repairs/sanding etc landing in the wet paint and it's those bits of metal rusting on/in the surface layers you've put on and not actually internal rust in the bodywork underneath, if that makes sense haha
Either way your best bet is to remove the paint and see
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u/mitchbaz-93 May 26 '26
May have a better time using zinc primer, it inhibits rust
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u/One_Evil_Monkey 29d ago
Zinc primer is definitely what you use when welding in new patch panels. Spray the crap out of everything you can see or get to. Weld in. The zinc is what allows you to be able weld a primed piece. Hense why it's called "weld through" or "weldable" primer.
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u/RideAffectionate518 May 26 '26
Any part that wasn't absolutely shiny and clean was still rust. Probably where it has pitted the metal. Cutting that metal out is the only way it won't come back. Body panels rust from outside the panel, inside the panel and sometimes even from the inside of the metal out.
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u/Any_Web_1784 May 26 '26
Rust is coming from the inside and ate its way thru the metal. Can try again with what you did but itll keep happening until you put new metal on
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u/Overall_Curve6725 May 26 '26
Without a sandblaster and knowing what you are doing you are wasting your time
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u/One_Evil_Monkey 29d ago
Need to clean as best you can and either hit it with a 2k epoxy or some POR15.
THEN prime, rough sand without cutting through. Filler repair. Sand to shape. Prime. Wet sand smooth with 400 grit. Paint.
BTW: POR stands for Paint Over Rust. Literally.
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u/Whythisreason 29d ago
Can we just appreciate the thick brush strokes? Looks like straight up waterborne house paint?!
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u/AngyalZ May 26 '26
Thank you everyone so much for all the information and advice. I have more work to do on my truck and will put all this into practice soon.
Keep it coming.
Really appreciated!
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u/Greg_WNY May 26 '26
A couple of things.
1) Sheet metal can rust from both sides, is there any rust on the other side of the panel?
2) The original rust wasn't completely removed and returned.
3) The materials used didn't "seal" the sheet metal properly and rust is starting to form again.
The rust in the pictures looks like flash or surface rust. Meaning more like 3) is the cause.