Got an 1977 JD 410 rusty-hoe. TSC sells a school bus yellow paint that looks close but how do you deal with large deep pitted rust spots ? Has anyone put a fresh coat of paint on their backhoe - do you have any tips ? Anyone ever use Rusty Metal Primer ?
There is also an acid etch you can prep the metal with but you really should do a sandblast or similar if you want the paint to last more than a couple months, 'rusty metal primer' will show the rust through in a while as it does not eliminate the problem.
I repainted my 1992 310D 2 years ago. I sandblasted all rust away and primed with epoxy primer then top coated with high quality poly urethane. I think that's the best way but very time consuming and paint and primer was expensive. About $1.200. Scrapping and washing off the old grease is also a big job. You may not wish to put that amount of cash on a 77. Unfortunately it's impossible to stop rust unless it's removed and sandblasting is about the best way.
This machine was once owned by an municipality - must have used it to load salt. The guy I got it from never keep it inside. Someone told me to make sure I put a hardener in the paint to keep dripping hyd oil from trying to lift it. It don't have to be pretty - just less ugly.
For a "less ugly" paint job rusty metal primer is a good solution. I use zinc rich primer sometimes, but I can't tell you which works better. A pressure washer with a turbo nozzle, or a straight nozzle will get you a decent surface with a lot less mess and time than sandblasting, especially if you use an acid after blowing off the loose rust.
Damn that's a good idea. Never even thought about use'n my powerwasher and I think I got a gallon of muriatic acid.
I have found rustoleum rusty metal primer to be about the cheapest and best coverage For really rusted metal. Found it best to paint over it just as it dries, otherwise, paint won't Stick, especially if enamel.
I wouldn't use muriatic acid. Phosphoric acid is used sometimes, it's the active ingredient in Naval Jelly type rust converters. I think sulfuric acid also cleans rust off of steel. Maybe somebody else is more familiar with paint prep. I know the "milkstone remover" you can buy at farm stores will do a decent job. Electrolysis rust remover would work for something like a rim or bucket that you could submerge in a big puddle. Might even be able to do the stick on the backhoe that way? I've never used it for something so big, but I can't see any reason it wouldn't work.
All of these acids need to be rinsed with water. Therefor the steel becomes brown before you can prime. There is a local ship repair company near me. I have seen them sandblast rusted steel ships many times before applying epoxy primer. If acid wash of any kind would work it seams they would us it.
I Googled 'using Muriatic Acid to clean metal' Here is a cut and paste of one response I found: The problem is that although it will remove the rust you see (actually what you see is NOT rust, it is the already oxidized byproduct of the rusting process which you can not see) it will set in motion a process that will lead to more damage than you have now. Once the acid contaminates the iron (ESPECIALLY iron castings which tend to be somewhat porous) the chemical reaction that starts will be nearly impossible to stop. Some will say you simply need to neutralize the acid, much easier said than done, and while steps to do this will slow the damage it hardly ever stops it completely. The rust solutions both dissolve the oxide on the surface and convert it to a phosphate that tends to stop the rusting process, Muriatic acid on the other hand will dissolve the oxides but as far as stopping the rusting process it will be like throwing gasoline on a fire! I have battled this for years on mining equipment that was exposed to Sulfuric acid and I can tell you that once the metal is contaminated it can really make a mess. It is not as simple as removing the iron oxides that you can see you must take into account the chemical process that you are about to start, and this is one that you don't want any part of! Do yourself a favor and use Phosphoric acid because it will remove the oxides also but it will start the right chemical reaction that will leave the phosphate coating that will inhibit rust instead of accelerating it. The Phosphoric acid may take a little longer but it is definitely the better way to go, usually the fastest way out of something just leads right back in!
If you get it down to clean metal, this stuff will stop the rust: http://www.por15.com/ Once it's on and dry, you can prime/paint over it.