How thorough should I sandblast old rust/paint before applying POR15/primer?

[pclausen]

So I got one of those 40 Lb. pressurized abrasive blasters from Harbor Freight to restore a number of implements. I have never used a sandblaster before, but it seems to work quite well (I got a 7.5HP 24 CFM compressor behind it). I'm using Black Diamond fine media (20-40 I think) from Tractor Supply.

I plan to prime and repaint my implements after removing all the rust. My question is how thorough I need to be in stripping the old paint before proceeding to the prime stage?

I'm working on a Woods RB850 blade first. Here are a couple of shots of the pieces after taking it apart:

Car dolleys are handy for moving these heavy pieces around!

I started with the blade itself, and here's what it looked like after working on one side of it. (the blasted areas on the other side is where the labels were)

And a little while later:

Should I keep going until the entire surface is completely smooth (as can be seen in the areas where there were labels), or will leaving it like this be good enough? (I do plan to hit those areas that still have solid paint). What I've done so far consumed 1 50lbs bag.

I picked up some grey sandable implement primer from Tractor Supply as well as this stuff:

For the Woods implements, I went to an auto paint store, and he was able to look up the Woods Burnt Orange in his computer and mixed me some Imron high gloss polyurethane as seen here:

So once I'm done sandblasting, I figured I'll hit everything with the Marine Clean and Prep and Ready. After that, I'm wondering if I should hit only the areas that had heavy rust with the POR15, and the rest with the Tractor Supply primer, or just hit everything with the POR15?

I was planning to brush on the Imron paint, but perhaps I would be better off picking up some thinner and using a gun?

 

[pclausen]

I think I figured out the answer to the last question myself. Reading the warning label on the back of the can of Imron paint, it would require a positive pressure, supplied air respirator to spray it. After looking up the cost of such a system, I think I'll be brushing it on using my $30 Tractor Supply respirator (which is NIOSH and organic vapor approved, which it must be based on the warning label).

 

[rjmack]

i would be very careful about sandblasting close to hydraulic cylinders... or am i being overly cautious?

 

[pclausen]

That's a good point. When I lowered the cylinder to re-position the blade, I head crunchy sounds. I stopped right away and cleaned the rod and blew off the sand from around the seal. Seems to be ok still. Nevertheless, I'll likely put the pieces on blocks from now on and only use the engine hoist to transport the pieces in and out of the shop.

It started raining, so I'll have to wait until at least tomorrow before continuing.

 

[crbr]

thanks for the pictures

 

[strum456]

Your Imron will only be as strong as whatever you put under it. I would take back the por15 and tsc primer and get some epoxy primer. The best epoxy I have ever used is made by southern polyurethanes. Look them up on the net, they will ship it to you for free. Putting Imron over tsc primer would be a complete waste IMO.

 

[shortthrow50]

i would be very careful about sandblasting close to hydraulic cylinders... or am i being overly cautious?

your being overly cautious. There is no possible way your gonna hurt that cylinder on the engine lift. You would have to be intentionally spraying at it directly but even so, you would have to be shooting it at one spot for awhile. I have one of those lifts that i have removed and installed about 10 engines and the thing has been smacked by everything in the book and still going strong.
OP- beutiful dog! i thout you didnt have to go that crazy with prep with POR. It is what it says paint over rust. A little is understanding but overkill would allow you to go with another product other than por

 

[AHNC]

One caution on the POR 15. I used it successfully...the second time I tried it. The first time I tried it I screwed up on the process and I was taking the stuff off in sheets. Second time, being very careful it worked out really well. Be careful. I kinda like the epoxy primer for this application. I wonder if the clean, etch, paint of the 15 will take well on the rough cylinder. Good luck

 

[Piston]

I'll be interested to see how this turns out. I want to do the same thing to my box blade but don't have a sandblaster. I'd like to have someone blast it for me but I have no idea of what that would cost. Good luck with your project.

OP- beutiful dog! i thout you didnt have to go that crazy with prep with POR. It is what it says paint over rust. A little is understanding but overkill would allow you to go with another product other than por

I've looked through the pics multiple times and I don't see a dog anywhere???? Am I just blind!

 

[rjmack]

I've looked through the pics multiple times and I don't see a dog anywhere???? Am I just blind!

chk the avatar. :laughing:

btw, i agree... beautiful dog.

 

[Piston]

:laughing::laughing::laughing:

Am I just blind!

I should have said, "am I just stupid"....that way you could have simply replied...

YES! :laughing:


EDIT: Pclausen, you just inspired me to update my avatar pic

 

[Mace Canute]

Yep, nothing neater than a GSD!

 

[pclausen]

Appreciate all the advice! I'll pick up some epoxy primer and take back the tsc primer. I haven't mentioned or shown it in any pics, but there is a significant built up of rust in the cavities on the center mount portion of the blade section. Same goes for the pivot assembly. The previous owner had the blade sitting outside and water would get trapped there I plan to use the POR15 stuff in these areas. I also have a 1970's era John Deere 45 3-16 plow that is very rusted that I'll be using the POR15 on.

Thanks for the comments about my avatar. That's Rufus. Here he is with his sister (Toska) back when he was just a pup.

All grown up checking out the cat.

And a couple of just Rufus.

His 11th birthday is coming up, but he's still as playful as when he was a pup!

 

[Piston]

Great pics of Rufus! :thumbsup:

 

[strum456]

I'm glas to hear you are going to do itt right, with epoxy. Now, what most people would do is they would go to their local auto paint store and ask for epoxy. Then when they find out how much name brand epoxy costs, they end up getting off brand stuff like Omni (made by PPG) or Nason (Dupont). Logic would tell you that it is relabled,and just as good. WRONG! Do yourself a favor and order some Southern Polyurethanes Epoxy. It is the best at ANY price, and you will probably save money vs most of the off brands. Just make sure to print out a tech sheet and follow it. Temperature is everything when it comes to curing epoxy.

 

[dweitzel]

The POR-15 works really well, but you MUST follow the instructions exactly for topcoating. The POR paint must be topcoated or primed while it's still tacky. If not, your top coat will come off in sheets as it won't bite into the POR-15 to achieve adhesion.

If you get it completely clean, and are sure no rust is present, go with anything you like. The epoxy will work better than just automotive paint. If you have a chance of rust left in pits and the like, you can't beat the POR-15. JMHO

 

[SPIKER]

I have used a good bit of the TSC stuff it works real well from what I can tell, look here I did a NEW build Dump Trailer in 01/02 era and it is still pretty good only spots rusty now are where large gravel or FEL have scrapped it up. I probably would not use POR on the Blade as it is somewhat SOFT and also not UV resistant. Use some good Phosphoric Acid to eat up the rust or if you have a good charger dip & use a electrolytic rust remover (electrically removes rust using welder/charge a soda solution of water and a day or two of electricity.) Been there done that on some top links that rusted up. search TBN for removing rust with electricity or maybe rust and washing detergent there are a few real good threads on how to do it.

album 9 pics dump trailer pictures by WPSPIKER - Photobucket


getting paint to stick is pretty much 95% surface prep and 4% paint mixing and 1% technique. I have been to PPG classes for surface prep work & how to use products correctly in the past. I built a lot of Power and Liquid painting systems booths ovens ect for may years.

The one thing to remember with Enamels is to add correct amount of Catalyses/hardners into the mix and only mix what you need to do the job at the time of the job is going on. Mix one spray cup full at time or if you are going to roll/brush just enough for job at hand. Thin first coat is best with a good tack time (not overly dry) than a medium second coat.

Yes Imron is very good, and it is from the 80s too, I painted imron on cars back then (probably painted over 100 cars in my body shop days & lots of equipment since then) the TSC paints are almost as good for durability which for implements is what you need high gloss on a PLOW or BLADE is well getting a bit anally challenged hahah (j/k) Remember if you are using these things paint is going to be scratched damaged and or worn off do yourself a favor and try to keep stuff working well first and looking good 2nd...


as far as Hyd Cylinders and Sand Blasting grit, yes the blast media can damage the chrome rod which can cut seals and cause fluid leakage.. The cylinder in the dump cart is damaged prior to me getting it for free. it is PUSH only and each full up stroke spits hyd fluid out due to sand blast damage it was a transport disk cylinder if I remember right that owner had blasted the plow by a young kid. it still works but leaks about 1/4 cup per lift when it is full. BTW use some Vaseline or grease to coat the cylinder Rod prior to painting in this pic.

Mark

 

[pclausen]

Ok, so based on what you guys are saying, here's my plan:

1. Continue sandblasting to get as close to bare metal as possible everywhere.

2. In cavities and such where I can't get all the rust out, use POR15 (following the POR15 directions), and apply a top coat of Imron burnt orange while to POR15 is still tacky.

3. Apply Southern Polyurethanes Epoxy Primer (gray) to all the remaining bare metal after prep (dry sanding with 80 grit).

4. Apply coat of Imron burnt orange within 7 days of laying down the epoxy primer, feathering onto the areas with POR15/Imron.

Does that sound like a good plan? Oh, and I'll wait until it gets into the 70s before applying anything. My shop is heated, but I don't want the mess inside. Besides, I can't have heat and be well ventilated at the same time when the outside temps are low.

p.s. Mark that dump trailer looks great!

 

[pclausen]

One other question. On the surfaces that slide against each other when changing the angle of the blade, should I just leave them alone and apply some grease during re-assembly, or give them the full treatment as well (epoxy primer, then Imron)?

The surfaces I'm talking about are marked with red lines in the image below:

Thanks!

 

[SPIKER]

with those sliding/rotating sections do not put any POR on there. again POR is a softer base designed to seal up rust and cause it to stop active rusting. Those sections should have very little paint more paint will only cause binding and scrape loose to roll up more.

again get some good phosphoric acid to remove rust especially in those areas. after setting kept wet with it the rust will be mostly gone and a bluish tint (looks a bit like oil on water) colored to indicate the acid has etched the area well. then no primer is needed just a two LIGHT coats of paint one light wet coat and a second wet coat from sprayer to keep thickness of paint low there. dont really need any grease there as grease will tend to hold dirt and or grime and cause more binding.

if it is pitted bad (does not appear to be) you could sand paint smooth and put a 2nd paint coating on after 1st dried. the paint on paint should slip and rotate easily enough just be sure to use a hardner in the paint.

mark