# Painting sheet metal



## BGS (Jun 2, 2013)

Hello Everyone,
This is my first time on this site. I have been business for 37 years so I am no "spring chicken" and I have not figured it all out yet!
I am perplexed over a metal building project and would like some input. I have done metal buildings before and used the Emulsa-Bond product, added to the paint. It worked very well.
Now I have a large building and it is old and some of the metal along the ground is rusted. I am going to use a rust converter to treat the rust. I was advised by the Sherwin-Williams rep to use the DTM Bonding Primer , followed by their Sher Cryl high performance acrylic paint.
The problem I am having is that we have pressure washed and scrubbed the metal, which has old paint on it, and there is still chalkiness left on it. Short of sand blasting or new metal, there doesn't seem to be a remedy for the chalkiness. 
My question is this: Have any of you used the S-W products under similar circumstances and does it perform over chalkiness like Emulsa-Bond does and would you add Emulsa-Bond to a primer or does that defeat the purpose of the bonding primer? Obviously, I am not going to offer any warranties on this project because they should just re-side it, but I am trying to make it work for their budget. WA-DA-YA Think???


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## Dustincoc (Sep 14, 2011)

The problem I'm seein g with your plan is that to effectively use the rust converter You need to get to both sides of the metal, otherwise it will just continue rusting thru from the back. This is assuming that that the rust has already gone thru the metal in spots. 

If your just dealing with a bit of surface rust on the outside or to remove the chalkyness, I'd either use a wire wheel for large areas or emery cloth if these are just small areas.

If you have the rust is on both sides and you have access to both sides, I'd suggest POR-15 rust converter followed with their primer, and topped with a paint of your chose. That is a bit pricy though. 

Of course I know nothing of metal buildings and am speaking in terms of how I'd deal with rust on sheetmetal.


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## We Fix Houses (Aug 15, 2007)

Just keep in mind the rust will return and advise so to the owner. Be careful what you warranty.

Many painters think if you prime, cover, seal over even the smallest rust areas to prevent ambient exposure you've got it licked...not the case.

Rust or properly called oxidation or auto - oxidation continues to occur unto itself even under the best coatings.

That said SW DTM has done real well holding up on a couple of jobs. Just did a pw to remove the chalk, then DTM.

I just re-read. Not offering a warranty is a good start.

I would not add EB to SW DTM Bonding Primer. Stick with what the label says
http://protective.sherwin-williams.com/search.jsp?Ntt=dtm&N=0


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## BGS (Jun 2, 2013)

Thank you very much. The problem is greater than I thought and I appreciate your time to reply.


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## painter213 (Nov 2, 2008)

What I have seen many times over is the one doing the pressure washing is not washing properly. They just whip the wand around and wet everything down and not really thoroughly. I tell guys and gals that they have to wash just like they are spray painting the surface. Complete coverage by the pattern and 50% overlap. And you need to have adequate pressure as well. Minimum 3,000psi. As far as rust converters, I call them snake oil treatments. They don't convert nothing. Just makes a hard shell over the rust. Now the DTM bonding primer is the right primer to use. The top coat, I have never used, but from what I read, sounds like it should be just fine. And just like you've done been told. Don't promise the moon on these type projects. Rust never sleeps.


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## stombaugh85 (Jul 23, 2012)

Pressure washing will not get the chalkiness off , only brushing it will With an acidic wash you can get most of it off.


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## Ohio painter (Dec 4, 2011)

The only addition I would make is to use SW Kembond primer to spot prime the rust spots. Then continue with the DTM bonding primer and then the Sher Cryl. 
If the entire surface is questionable then I would use the Kembond as the primer coat and cover with the Sher Cryl. The Kembond is not tintable so if the finish coat has some color to it then 2 coats of finish may be needed. 

I too always used the emulsa bond products but I have got away from them as they really are not necessary. 
Hope this helps.


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## Derek1157 (Dec 21, 2012)

You can only do so much for this type of thing. You're basically just buying time by setting up several layers of defense before the rust comes back. DTM Bonding primer is great. So is Kem Kromik. So are some of the zinc clad products. Zinc clad has a "self healing" technology that really slows down the oxidation process. SW has several dozen products like these that are all very similar. The differences are that some have 1 or 2 specific attributes such as adhering to a chalky surface. Some will cure in moist conditions. Some are anti-rust. Some are rust- resistant. Some are anti-corrosive. On and on and on. 

I'm not sure which ones perform on chalky surfaces, but I'd guess that DTM Bonding primer is one of them. These all have more than twice the adhesion strength of regular(architectural) coatings also. If I remember correctly, the entire DTM line of products is rust inhibitive or rust resistant, or some flim flam or other.


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## Derek1157 (Dec 21, 2012)

I just realized you're from Montana, BGS. Where about? I was raised in Great Falls. Lived in Helena too. Got family all over there.


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