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? :)

I'm no professional, but I use my trusty DA sander to smooth sharp edges and remove rust at the same time. I only worry about degreasing if there is a noticable spot after I'm done sanding.

Greg, just my 2 cents, but I would just sand the control box door down and start over. I suck at painting, so matching the spot where I clean off drips is usually harder than repainting.

Moved from another thread:

Thanks, this will be the last drilling on the gantry. At the moment it is outside...to collect some rust before painting. On that note...is painting done with the rails in place or is it better to paint the loose parts by themselves and then assemble it.

I did loose parts first and then touched up paint after shimmimg and alignment.

I also did loose parts. It works better for me.

come on rust :D
On some of the lasercut parts it looks like the laser process BURN't the oil onto the metal...Hard shiny black surface. Suppose the best is to sand it down with a flapper disk.

I am not very much experienced with paints,
Should I us 'Red Oxide' primer paint, which is commonly used here or should I use other specilised primer ?
Also should I apply putty after primer or before primer??

Thanks

Hi Sharma,

get it all sand blasted and powder coated.

RGDS
irfan

I'm no expert on paint but I will tell you that I used red oxide primer and I applied the putty after the primer.

Thanks Doug,
Did you apply another coat of red oxide over putty ?

Sharma,

No. I probably should have but I was ready to cut so I just painted over the putty. I'm happy with it.

I've been out of town for the past few days and while I was away, I remembered that Gerald recommended against powder coating because he said that it makes it difficult to make changes later. I agree with him. I've made a couple of changes and additions later and it was simple to touch them up with a spray can.

Thanks Doug,
I am painting it myself with spray gun I have. Later after shifting and adjustments, retouching will be necessary, then with same remaining paint it will be uniform. So what Gerald suggested is well thought of.

Mill Scale
 

If sand blasting is not a piratical implementation, buy rust covered steel; With a thorough wire brush, the mill scale will come off with the rust.

Apply diluted salt solution helps accelerate the rust formation as well. I never tried vinegar, but salt solution is so much cheaper.

This is a common practice in my trade.

Hope this helps.

Rust removal
 

If you do not have sandblaster by the hand...
We use acid for removing oxides from metal surfaces.
Ex. Use citrus acid diluted for copper.
Ex. Use HCL or Phosphorous acid for steel.

Of course you first remove mechanically all the big stuff.

Phosphoric acid (read the label on your favourite soft drink) leaves a coat of phosphate on the steel. Also removes the mill scale, but takes a while. It is better to remove all the big blotches of rust with a wire brush/flap disk. Phosphoric acid doesn't prevent rust from forming but it makes the paint stick better to the steel. Dip/wash steel in acid, wipe with a cloth to remove nibs, paint as soon as dry, otherwise rust will form very quickly. Blemishes can be filled with body putty (raid your wife's vanity cupboard, no just joking!) Lightly sand with 220 water paper between coats to get a good finish.

I am very impressed with how well this item removes heavy rust. I know most of you have seen these in action but this was my first time using one. Screw it on to an angle grinder and go.

On the Harbor Freight website it shows one mounted onto an angle grinder with no guard. It is typical to not use the guard for this type of brush? No guard, safety glasses, and gloves, is that safe enough? I left my guard "better safe than sorry" but it seems the tool would be more effective with out a guard.

Chris, It may be more effective at removing skin without the guard. :) I think they left it off for the pictures so you could see the product. I always use a guard with mine. I like the skin on my fingers.

Safety glasses are most important with that tool. Skin grows back but eyes dont. I personally know two who had little piece of wire on eye. One hasnt luck and is on one eye blind.

My paint system
 

I would like to share how i will paint my MM.

I used to work as a painting inspector for Hempel Coatings. My job was to visit the shipyards, steel construction and container manufacturers and advise on the correct use of the Hempel paints.

In my opinion Geralds advise in post 2 is right on the spot.

A cheap but good quality and easy way to paint is to use an alkyd paint system and apply the paint with a brush and a paint roller. http://en.wikipedia.org/wiki/Alkyd

It will not give you the smooth finish of spray coated paint or the durability of a gritblasted and powder coated system but it will be more than sufficient to protect your MM from corrosion and it will look good.

Use a brush first to apply the paint in all the difficult to reach areas like corners and recesses, then use the roller to apply the paint on the flat surfaces. Use a round brush and a lacker roller.

Alkyds can have different names like "phtalic ..." and other exotic descriptions but if it says on the can to use white spirit to thin the paint or to clean the brushes than it very likely is an alkyd based paint.

I will use two coats of primer then apply the caulk and then apply one or two coats of topcoat. Each coat not more than about 50 microns in thickness. More paint is not allways better!

Alkyds actually are two component paints, the "curing agent" being oxygen from the air. They will crosslink and form a tough coating. Because alkyds are "oil" based alkyd primers will adhere well to a properly prepared surface.

Don't use alkyds over galvanised surfaces. The paint will turn into a form of "soap" at the contact surface with the metal and will peel off.

Happy building,

Bart

We have a paint guru in the house!

Alkyd paint, I think they are commonly known as glossy paint. A good option for those (me included) whom doesn't have spray paint facilities. I always has that impression of high paint losses when spraying skeleton structure, and require great length site preparation if one don't wish to see patches of paint all over the place. These are the excuses I can come up with for the moment to delay buying that air compressor in the hardware store 2 blocks away...

It does take lots of patient & skill to produce good hand brush job.

If I remember correctly, except epoxy & Zinc Chromate nothing goes well on galvernised surfaces.