steel cleanup, suggestions for degreaser

DazedConfused · Apr 28, 2006

Hi all, we have been making some gates for the back yard of a friends house out of square section steel tube, fabrication nearly finished, but now it needs painting. The gates are: 2 of 8'x4' and 1 of 7.5'x3' hinged on a frame of 2" square section steel, 8' tall and an 11' crossbar between posts.

We are scratching our heads over the best/easiest way of degreasing the steel before painting it. Acetone works well, but our supply is limited, and we are going through loads of rag/paper in the process.

We don't really want to go down the route of a wash off with water type degreaser, since that would mean then having to dry it thoroughly before painting to avoid the dreaded rust.

Any suggestions?

Thanks,

Chris.

Michael Az · Apr 28, 2006

I guess it depends on the quality of the paint job you want to end up with. If I wanted a top notch job, I would sand blast the gates, then primer with Zero Rust and then a good top coat. Other than that you will just have to scrub them clean. How about laquer thinner? I don't think there is an easy way out.
Michael

Forrest Addy · Apr 28, 2006

Acetone is expensive. I use mineral spirits paint thinner. It does the same job for 1/3 the cost. You'll need two applications and a lot of rags to get to bare metal. When the wiping rags come off clean, allow it to dry then follow with Comet, water, and a scrub brush. Then inspect and detail removing all sharp, drilling any drain holes necessary, and ensuring all work is complete, I always miss something.

Follow that with a phosphoric acid metal prep. This converts all rust and provides a grip for the first coat of paint. Scrub off the metal prep resudues using only water and a soft brush like a toilet brush. Wipe dry and allow the sun and wind to dry the piece completely.

Prime and apply two color coats of your choice of industrial coatings knowing you covered all the pro painter's steps.

Peter from Holland · Apr 28, 2006

Sodium hydroxide (NaOH), also known as lye or caustic soda, used in a mild solution works the best for me for degreasing,also machines Desolve in water and waight some time It even works if it is all poluted
Wear glasses and gloves

surplusjohn · Apr 28, 2006

hot sudsy water, a scrub brush on a sunny day followed with phospate prep per above is ideal. blasting even better. Solvents may dissolve but they also thin out grease, ie spread it around, detergents suspend and remove it, that is what you want.

DazedConfused · Apr 28, 2006

Hi Guys, Thanks for the suggestions, hadn't crossed our minds to use paint thinners (Doh!), and yes, the acetone is expensive, prefer to save it for welding aluminium.

We now have one of the gates painted up, but it was clear we needed to scrub them up better due to the primer not giving complete coverage - spots opening up in the wet primer showing the metal.

The quality of the steel is good, and we are pleased with the surface finish of the one we've currently painted. I'll try and post some pics once we've got them installed in their new home.

DazedConfused · Apr 28, 2006

Sunny day?!! This is the Isle of Man! It has no problems raining solid for a fortnight!!

dfw5914 · Apr 28, 2006

I know it is too late now (gates built). I found that I can save a lot of time by at least priming the parts before I weld them into assemblies. Just leave the weld areas bare or grind off just prior to welding. Spray on oven cleaner works best for cleaning prior to paint, it will even remove light rust.

Pete28 · Apr 28, 2006

Best is sand blasting, but that's more of a production set up. Next best is detergent and water with a good stiff brush. Let dry well. Then prime and paint. Check out the Grainger catalog for a pretty good rundown of paint properties and applications.

DazedConfused · Apr 28, 2006

DFW - we are planning to do just that for the frame to hang them off, the welding heat when assembling on site will dry the paint a treat!

If this picks up, might consider looking into sandblasting eqmt, previous experience (15+yrs ago) was that it was a bit slow for my liking, though.

Stopped for the night now, feet up, wine out!

Have Fun!

jimbo1490 · Apr 28, 2006

Ketones like Acetone and MEK are useful as a final cleanup to eliminate even the tiniest residues just prior to priming/painting. But ketones are pretty useless for general degreasing; they just wind up spreading the grease all around. Plain mineral spirits works well as a degreaser but leaves a slight residue which you may want to remove depending on the paint system used. You can follow up with a wipe with a ketone and clean rags to get it squeaky clean.

Another good cleaning solvent is naptha. It cuts through grease very well and evaporates quickly and leaves no residue.

Follow up your cleaning with either and acid etch step OR an etching primer, but doing both is redundant. The rust converter type products all qualify as etching primers.

A set of sliding gates I prepped and painted back in '86 using Extend and latex enamel still looks good with NO rust through anywhere. We have been careful to repaint them every 4 years or so but have not as of yet had to strip or gring to address any rust break throughs.

Jimbo

Jimbo

Evan · Apr 28, 2006

Use oven cleaner and then rinse it off with boiling water. The heat from the water will cause the metal to self dry in just a few minutes with no rust or wet spots.

Thermo1 · Apr 28, 2006

If the steel does not have mill scale on it, you probably can get by with a regular clean up. Mill scale is probably the #1 enemy of painting metal. Water gets through the paint film, and under the mill scale, and starts to rust underneath. Since rust has a greater volume than steel, the mill scale pops, taking the paint with it.

Sandblasting is the recommended way to remove mill scale, but it is slow, and requires at the very minimum a 1 hp air compressor. With that you can use fine sand, and slowly do the final cleaning of steel that has been cleaned up by other means, perhaps with sanding discs in a portable grinder. Sandblasting works. About 15 years ago, I repainted a cast iron railing outside my house. This is the typical Victorian railing, with lots of detail. I cleaned it as well as I could, then sandblasted, and primed the same day. This last is an important step, as it prevents any little bit of rust forming. I used a Rustoleum brand bare metal primer, and one coat of Rustoleum topcoat. Have not had to repaint since.

If your steel does not have any mill scale, count your lucky stars and clean and degrease one of the ways suggested above.

Thermo1

DazedConfused · Apr 29, 2006

Evan - good tip about the boiling water rinse, could be just the thing we need.

Thermo1 - lucky I have a 2.5 hp compressor then! looks like a good excuse, sorry - reason, to expand my air tool collection when I get some spare cash.

Jimbo - we are always interested in solvent abuse

- where would a private individual be able to source naphtha from? I could get it at work if I had a use for it (scientist) but taking it home would be stealing!

Off to work soon, then we are going to start final prep and assembly this weekend. Hopefully it will all be over by Sunday.
I'm not sure they realise just how big this set of gates will be, their brief was just "I want to park the car in the back yard, and get a hire van in there sometimes if needed."
Maybe they will get just what they asked for!

jimbo1490 · Apr 29, 2006

You can still get naptha in Qts and Gals at any home center. They sell the VM&P type (Varnish maker's and painter's) rather than the higher 'dry cleaning' grade. I used to keep a 5 gal pail of the dry cleaning type aroud but have not since the crude oil price has made these solvents so expensive.

Jimbo

Low-Alloy · Apr 30, 2006

For removing oil/grease I use Zep's Big Orange-- PROD. #0415 .D-LIMONENE (orange distillate). I find it cuts oil/ grease as well as mineral spirits and I don't have to have the shop full petroluem fumes after I use it. Works great for cleaning wrenches and other tools used for automotive repair. It dry's pretty fast, it is combustable and latex gloves won't last very long in its presence.

This is not the stuff you buy at Lowes or Home Depot.

DazedConfused · Apr 30, 2006

Update:

gates hung in position, "goalposts" anchored to walls with 12mm studding resin fixed into walls. Plywood 1/2 way there - fixed in position but only half stained. Looking good, last few bits needed to finish off are the closure fittings to the frame. Will post pics once it is finished off and painted up. They are big enough to drive a transit van under with about a foot clearance above the roof.

Thanks for all the tips on degreasing and prepping for painting. Watch this space.

DazedConfused · May 9, 2006

Well Guys, Job finished!

Attached are a few pics of the completed gates, pity was, in our haste to get on with the job, we forgot to get some "before" pics!!

Many Thanks for the help rec'd, some very useful info.

Enjoy!

Chris.

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