Ok so I have been repairing the driver side fender and there are numerous smaller rust holes. I am having a hard time filling them with out creating a bigger hole. So i was wondering if I could just not fill them? I have cleaned them and rust no longer exists there so could i just primer and add filler? the holes are no bigger than the eraser on a pencil. Almost all of them are smaller than that.
can you get at the back? because if you leave any rust untreated with acid, before primer and filler, it will come back. Scrape and sand off the paint, and bad metal. Treat rust with phosphoric acid to neutralize the rust. If you go to home depot in the paint dept. they have it. OR "Ospho" at a marine chandlery. this is a very important step. Dry overnight. Now the metal is stable. Prime metal with a two part metal primer, to seal the metal. Interlux 2000 or Proline 3066-1 (my favorite)(marine primer paints) Sand a bit then apply filler material of choice. West Systems epoxy, thickened.. or Evercoat brand Formula 27. A polyester filler will work. Sand that and put more primer. Top Coat.
gotcha thanks! What about the rust remover naval jelly stuff from napa? is that the same as the phosphoric acid mentioned above?
yes same. the more "liquid" the better...for penetration. it's phosphoric acid, whatever the brand, and it will change the iron oxide "rust" to inert and black iron phosphate. Sometimes it takes a few applications.
ok just a few other questions for prep then. The naval jelly directions say to apply and leave on for 15min. longer if rust is bad and then rinse off. Will it flash rust after? im guessing not. Do i just rinse off the naval jelly, wash (i used the flake type clothes detergent no fragrnace or any of that), rinse, and then when it dries primer? Or should I use a paitn prep cleaner after i wash and rinse and it dries?
dont wash with soapy water.. just water. and yes, water makes new rust. Better yet, wipe it off with acetone..gloves, breather mask. Some brands (Ospho) say to let it dry, and that it is a primer. then prime and paint. These are the best. I have used both, and I really dont like the "wash off" ones. The ones that say wash off relly mean it... I tried without washing once, being used to the higher potency Ospho, that makes a clear shell over the now black once rusty metal. It caused the primer to lift, as it left a residue. I had to sand it all off. The Ospho or other clear or green liquids that dry on are the ones of choice! Paint prep?? I used Acetone instead of water because there was NO WAY I was going to put friggin water on bare metal, then prime...OMG.
I'm no expert but I'll tell you what worked well for me. I liked using OSPHO. If you wet the rusty area well and let it sit for 15-20 minutes, then wet it well again and wire brush it and then wipe it off while still wet most of the rust will come right off. Even heavy surface rust will clean up and look like bright new steel. There's enough OSPHO left after you wipe it off to seal up any microscopic rust. Let it dry thoroughly and then I wiped it down with lacquer thinner before priming to remove any residue or dust. I had some quarter skins that had been sitting around long enough to have some pretty heavy surface rust. That treatment made them look like new.
My opinion: NO "treatment" is an effective solution for rust holes. The only solution to replace holes is new metal. I think you will find that within a few months to a year....all of your work will be bubbling with rust.
i did mine perfectly and still, 7 months later i see the start of bubbles on m quarters behind the doors and bottom edge of a door = wasted paint job should have just got new doors and quarters..but shipping quarters here was like 350usd alone for that.
as said,if there are rust holes they need to be fixed.the holes may be small but the metal around them is very thin also.if its pretty easy to take the fender off.i would cut out anything that is thin and replace it.with the fender atleast after the metal is welded in it can be preped and painted on the inside.even if you cut the metal out,weld in new,if you dont coat the inside it will rust!!!
rust is cancer ,sometimes the chemo works most of the time it will come back later after it gets wet cut it out and weld patch panels in if you plan on keeping the car naval jelly only treats the surface not the inner layers of the metal,
small holes another idea you can try when welding small holes with a mig is putting something brass behind the hole , be sure its tight against the back of the hole and then fill the hole with small quick spot welds , the weld will not stick to the brass and it serves as a heatsink and gives the weld some backing to help you fill the hole in . !!
I had the same problem with my maverick welding the small pin holes in my fenders was like trying to weld tissue paper lol i droped the heat down a little bit and got them welded up but a good rust killer is POR 15 its basically paint but its the most heavy duty rust killer preventative on the market you can buy it at any local body shop supply place its about a 140 bucks for a gallon but well worth the money you will never see rust again i did 3 coats on the underside of my maverick its so crazzy that gas laquor thinner wont even touch it lol but if you can get your hands on some POR 15 definitely use it its well worth it
They sell small cans of Por-15 as well. I have seen it in quarts and I beleive pints as well. A little bit goes a LONG way.
When you use POR 15, don't use the paint directly from the can. Pour small amounts into another container and apply from there. When a brush is repeatedly dipped into the paint, the paint can get contaminated and the whole batch will set up and be unusable. Don't dump any that has had contact with the brush back into the original can.
