Rebuilt/New tractor slasher paint help

G'day Everyone

I am currently rebuilding a tractor slasher for my Dad. It is actually more of a new item as I have rebuilt the gearbox with new bearings and seals and the actual slasher deck I have completely fabricated with new steel.

All of the steel I have used has been either soaked in hydrochloric acid or vinegar to remove the mill scale to improve the welding process and for better paint adherence when i paint it. Post mill scale removal I dried it all down and wiped with turps which has kept flash rust at bay. In the couple of areas where I have faying surfaces i have coated both items of steel with cold gal to help minimise rust if water was able to find its way in.

I am nearly up to the painting stage and I would like to ensure a good quality finish without spending a fortune on paint as well as realising that it is a slasher and it will get beaten up a bit, particularly the underside.

I am going to do a hammertone on the top and sides with probably just chassis black on the lower surface with the understanding that the chassis black will mostly be gone after the first use. Where I am stuck is the preparation/undercoat.

As much as I have tried to ensure there is no rust inevitably there is a small amount visible (fingerprint areas etc). I am thinking of either sanding it back with emery in a sander and then clean and apply etch primer, then top coat. The alternative is to leave it but coat with a combined rust converter/primer (probably a hitech product or similar seeing as they are no longer in existence) and then either paint en etch primer then top coat of just do a top coat straight over the rust converter product. The benefit of this way is that I don't need to be 100% sure of removing every speck of rust.

I have two questions:

1) What is the best way to prepare/undercoat etc prior to top coat

2) What is a recommended hammertone paint to use? I am currently considering a Septone product seeing as Rustoleum is no longer in existence for industrial products.

Thank you for any assistance that can be provided.

Cheers

Yozza

All I've ever done, is given the metal a good clean with turps or similar, make sure it dries off, then give it 2 good coat of a red oxide primer, I think my last one was with the Kilrust brand.
I prefer the 2 coats as inevitably I miss a few spots, so the second coat covers it.
This is probably more than the manufacturers do, I think they just give it a coat of finish colour and that's it. It's more important that any areas where moisture can get trapped, that it is sealed properly.
HTH
Kryn

I would not be using Hammer tone, I would use something tough Like agrinamel and red oxide primer

I have been using Rust Blast
https://www.kbs-coatings.com/rustblast-directions.html

It leaves a zinc phosphate coating to protect the steel. Zinc rich coatings do not work well under a lot of top coats, I would be using an epoxy primer or an etch primer before your top coat.
I would look at what recommendations there are for the topcoat that you choose.

In the auto trade

Talking as a ex paper beater.

New or repair, steel Panels in our case.

Wipe down with Prep wash(just use some paint thinners).
One light coat of Etch primer.

Two or three coats of primer,
Then a Guide coat.

Sand primer, apply more primer if needed or break throughs.

Then your Top coats.

Prep Wash between primer coats too.
Most Auto stores will have all that stuff on the shelf!

Hope that helps,

Cheers Matt.

Ill throw another point of view out there because thats what forums are all about :wink:

I have been painting old tractors and machinery for decades for my old dad and all I have ever done is use a quality enamel straight over the steel!! Sure priming with a decent primer would possibly be better however all the work I have done has stood the test of time.

Now after giving my opinion on the topic I wont mention what my trade is :oo:

Attachment 388634

The last slasher I tried to dolly up was a complete paint fail. I think I sprayed the cleaned-up top of the deck with silver gal paint, then finished with a couple of coats of Rust Guard epoxy enamel. A couple of years down the track, I'm pretty sure every square inch of that enamel has peeled back from wherever the silver paint was.

That said, that slasher had/has a pretty awful life. When I got to it, the rotor was banana-shaped, with the blades tearing holes in the top deck when they were deflected up from hitting a rock, so ultimately, my poor painting effort was the least of its problems.

Thanks for all the reply's and advice, it is appreciated.

My preference has always been to use some form of industrial/agricultural paint but i have struggled to find some paint during lock down times and that is a reasonable price. Previously I have used Rustoleum agricultural paints that i have found to be really good but they (Rustoleum/Hitech/Motorspray) have pulled out of the Australian market except for hobby interior paint.

I have found the Agricultural Enamel produced by Wattyl that was suggested by China but now just need to find someone that has it in stock.

Simplicity mentioned etch primer then coats of primer, can i just top coat over the etch or do I need to do another primer coat? It is a tractor slasher so there is no need to go to the extent of guide coats etc, reality is i want it to look good and get 5+ years of it sticking to the metal remembering that it will live outside and get beaten up a bit!

What is the general view on removing the slight surface rust (very light) mechanically or just convert it?

Tghanks again for all the input.

Cheers

Yozza

I've had good success with longevity from the hammertone paints - just straight on clean steel. I usually just grab it from Bunnings so will most likely be either Dulux Metalshield or the White Knight stuff.

My view is unless you're going with an engineered paint system of matching primer/undercoat/topcoat etc then best to stick with just a single step one. Mix products etc and you're likely to end up with poor results.
The hammertone's are meant to be OK to go on without primer on clean or lightly rusted steel and in my experience they work well done that way. I've got 4WD wheels that were done about 8 years ago and have had a hard life. Sat out in the sun, mud/dust/sand etc and the hammertone is still OK.

Out of interest, the other week I had some left over in the tray after painting my T&C grinder, so I thought I'd just roll it on my gantry frame which is the typical blue primed SHS. Wiped it down with some wax and grease remover, and rolled some on.
I ended up sitting a nut on top later on without thinking and it must have been still tacky. The next day when I knocked the nut off it peeled a big strip of hammertone off. Obviously it didn't stick to the blue undercoat on the steel - lesson learned.

You also mentioned chassis black. I've had a good results out of the 3M Chassis Black that you used to be able to buy from Supercheap. Again, direct on bare steel.
Not sure how it goes with constant exposure to UV though, and I vaguely recall something about it not being so good in that respect. Not an issue if its on the underside of a mower though.
My ride-on mower deck just gets a good spray underneath with fish oil from an aerosol can if I happen to be doing any work on it. The stuff penetrates into everywhere, sticks like dog crap, and just seals the rust out is my experience.

Steve