In our shop...the environmental way for us is to use simple green in a pressure washer to degrease. Scale - vinegar does work well, but takes a while. Sean

There is an easy way to get rid of mill-scale . . . . . . buy steel that is clean. Shop around and be fussy with the suppliers. The dirty steel is kept for the guys who aren't fussy.

Another beauty of laser cut steel is that the stuff is absolutely clean - the laser doesn't like the mill scale either.

For degreasing we use an emulsified kerosene. In the can it looks and smells like kerosene, but it is totally water soluble. Turns white when water mixes with it. Apply it all over by brush, spray or dip and it dissolves the oil. Then rinse off with liberal quantities of water until the whiteness is gone. (Similar products sold here as engine cleaner or paint brush cleaner - ours is called Tekprol 131). The key is to rinse the dissolved grease away before the kerosene dries. After degreasing with this system, light red/brown rust is seen within 30 minutes!

Hot rolled versus cold rolled
 

Hi All,

If it is your intention to paint the steel, specify hot rolled steel versus cold rolled, cold rolled is done under a flood of oil to lubricate the rollers, this oil becomes inbedded in the surface making painting very difficult.

Regards,
Greg

Bear in mind though that the cold rolled is usually more accurate and consistent in size - this usually only applies to round, square and rectangular tubing, lipped purlins, lipped channels, zed sections and top hat sections (max wall thickness 3mm) - the channels and angles are almost always hot rolled.

Greg, do your suppliers offer you a choice between hot or cold rolled for:
- angle iron
- channel iron
- round pipe
- flat bar
- square/rectangular tubes
- laser cut plate?

For cleaning rust, paint, oil and even powdercoat a method soda blasting is very effective without wearing on the base metal unlike sand which wears away the metal along with everything else.
http://www.ace-sandblasting.com/soda...g-article.html
http://www.mikesmediablasting.com/

I have to laugh when I read these statements:

". . . . . uses safe, edible baking soda instead of sand. . . . . Unlike sand, which must be swept up, and whose dust is dangerous, baking soda is harmless"

Sand dangerous? We live and play on it and clean sand (silica) can be eaten - it is inert and indigestable. The baking soda/old paint doesn't have to be swept up? Oh yes, sand is not good when you get it in the lungs, but who has said that it is safe to breathe baking soda....mixed with old paint?

I am going to have to close this topic soon - it is getting too exotic :)

Gerald,
Now now, you know you can't believe everything you read, and that is not the point I was trying to make. Mainly avoiding eating up the metal along with the abscence of chemical pollutants.

Couldn't resist Tom :)

There are zillions of ways to clean and colour steel. Everyone has an opinion on it. There must be other forums that do this subject more justice. Don't want everyone slowed down in their builds by procrastinating on how they are going to paint it.

Painting new steel
 

A question for you guys that have painted already. Do you remove that grey/bluish scale that is on new steel before painting ? The only way that I can see to get down to clean bare metal is sand blasting and that will be a lot of messy dirty work. I would prefer not to do that but I will do anything I have to do to do a good job. I have a HVLP sprayer for painting an automotive urethane paint but preparing the surface properly is important. What did you guys do? Please describe the steps you took to prepare and paint the beast.

Thanks
Paul

Paul,

I just started painting and here's what I do. Let's see if it's correct with the crowd. :)

1. Remove all weld slag and splatter with wire wheel (also use some new synthetic wheel, don't know what's it called) and scraping with chisel.

2. Remove all rust with wire wheel.

3. Remove all grease. I'm using "Acid-tone" (not spelled correctly).

4. Apply 2 thin coats of primer.

5. Apply 2 thin coats of MechMate blue.

I don't remove the "blue" coating to bare steel. I have a small sand blaster, and if my procedure is not proper, then I'll do it again the correct way. I should note, on the skate, I did sand blast to bare metal.

Not sure where it is without looking, but there is a whole thread on metal prep.

How right you are Greg,

And it's right below this thread.

http://www.mechmate.com/forums/showthread.php?t=484

I'm a late comer to this thread, but having done a lot of home machine rebuilding over the years I have found that not all paints are created equal. One of the best paints I have found for painting machinery is Hammerite, it can be applied to rusty surfaces after loose rust is removed. It comes in two different finishes, the original was a hammered finish, ideal if the surface isn't perfect, and more recently in smooth. It is thicker than normal paints and can be either brushed or sprayed, it is fairly fast drying. It is highly popular in the UK and Europe, more difficult, but not impossible, to get in the US.
If you do use it be sure to buy plenty of thinners, it is not compatible with white spirit or lacquer thinner.
Rust-Oleum is a similar US product, but IMHO not as good as Hammerite.

Copied from another thread

It is a great feeling to see some MM blue of my own.

http://i36.photobucket.com/albums/e3...P1010012-5.jpg


http://i36.photobucket.com/albums/e3...P1010008-4.jpg


http://i36.photobucket.com/albums/e3...P1010006-7.jpg
http://i36.photobucket.com/albums/e3...1010004-11.jpg

mmmm. automotive paint. nice :)

Ouch,
My eyes, my eyes. :)

Sean

The paint is Imron 3.5 HG Industrial. It is used on park rides, industrial machines etc. It is a single stage two part paint great stuff... It is the same as the automotive Imron 5000 but much cheaper. I have been using it for sometime now and love it. Thanks for posting

Gene,
Is that paint hard to find? I really like the finish. What kind of thinner does it require?

The paint can be bought a most auto paint stores that sell Dupont products. it is a two part paint so you will need to buy the paint,activator and urethane reducer.also if it is cold when you paint you will need a accelerator.

Paint is Imron 3.5 HG
Activator part# VGM-6005
you need to ask the person at the paint store to give you the same brand of accelerator.

(NOTE This is very Toxic paint so Please use a NIOSH Respirator)

http://www.bennette.com/pdf/Imron3-5HG.pdf

For the folks that will ask what gun do you use. I have a $550.00 Sata jet Digital 2000...But get this my $14.99 Harbor freight gun puts down a better finish. so if any of you have ?s on what gun to buy. Dig deep into your pockets at get out that $14.99. I use the harbor freight gun on everthing I paint.

47016-4VGA
Central Pneumatic Professional 20 OZ. GRAVITY FEED SPRAY GUN.
Online the gun is listed for $24.99 in the store it is $14.99

Gene,
Interestingly you mention the HF gun at 15 dollars. At my shop, where labor cost more per hour than the cost of 3 guns....I buy these by the case. It's easier to toss-the-gun after spraying some materials than actually cleaning it and paying the guy to sit on the clock and "clean up everything 3 times".
...just the penny pinching boss man talking :)

Gene,

Nice paint job. But I'm going the South African rattle can method.

Well, wait a second, $15 for a spray gun, ... hmmmm ... the rattle can's I'm buying now are $5/ea ... let me price a gal of Imron 3.5 HG and activator and rethink this paint job. :)

Gene warned us about his paint - see post #24 in this thread :)

I have a hypothetical question. Suppose my "friend" was painting and had a couple of runs in his paint job. Not bad for a beginner.

I'm assuming that one just wet sands with fine (440 or greater) sandpaper and re-paints. After its had plenty of time to dry. Is that all one does?

Amazing, my "friend" is using a high gloss MechMate blue. Aside from the couple of runs / errors, the first topcoat looks pretty good. ;)

Greg,

Tell your "friend" this he has completely ruined his whole machine and it isn't salvagable. However, if you will give me his address, I will haul it off immediately, free of charge.:D

Doug,

Well ... uh .... OK, it's me. I wouldn't give up / sell / barter my "number 1" MM for all the gold in the world.

Painted everything today and went pretty good. Had a "paint run" on the control box front cover, of all places. I'll give it a couple of days to dry and touch up that spot.

I don't wait for runs to dry - that takes too long, because the paint is thick. I wipe them them off ASAP and let the thin paint dry quicker before the repair.

Aaaah, that make sense. Thanks.

I only have that one run on the control box door. :mad: It'll be a couple of days before I need it.

What, nobody is going with the $7000 holographic paint that changes colors when you look at it from different angles? :)