# Exposed ductwork



## Stretch67

Sneaking in a small commercial project before spring shows up. They're going with the "exposed bar joist exposed ductwork" look like Chipotle etc. We gotta paint it all of course. It's pretty clean, we wiped the dust off all the ductwork with dry rags. R u guys taking the time to solvent clean or etch it(galvanized ducts)? Or just start spraying? SW waterborne Acrylic Dryfall

Sent from my SM-G930T using Tapatalk


----------



## PRC

bryceraisanen said:


> Sneaking in a small commercial project before spring shows up. They're going with the "exposed bar joist exposed ductwork" look like Chipotle etc. We gotta paint it all of course. It's pretty clean, we wiped the dust off all the ductwork with dry rags. R u guys taking the time to solvent clean or etch it(galvanized ducts)? Or just start spraying? SW waterborne Acrylic Dryfall
> 
> Sent from my SM-G930T using Tapatalk


We have never solvent cleaned new deck/bar joist ceiling if it's getting acrylic dryfall. No failures yet in 18 years. That said it is probably the right thing to do. It might bite us one day but with dozens under our belts we feel pretty comfortable doing it this way.
Only one that had to be cleaned was a repaint in a brake factory for trains. Everything was covered with a layer of brake dust. That one got oil dryfall.


----------



## Stretch67

PRC said:


> We have never solvent cleaned new deck/bar joist ceiling if it's getting acrylic dryfall. No failures yet in 18 years.
> Only one that had to be cleaned was a repaint in a brake factory for trains. Everything was covered with a layer of brake dust. That one got oil dryfall.


Not worried about the bar joist. Mostly the ductwork 

Sent from my SM-G930T using Tapatalk


----------



## kmp

The last one I did, and we used S/W dry fall, I etched the duct work. Didn't really have to but wanted to be safe.I only rinsed it once and the finish coat had weird blotchy spots. They went away after a touch up coat or two. I needed to rinse it twice. I used semi gloss dry fall and I might not have had the problem if I would have used flat.Exposed structural is such a dated look that I don't like and I really hate painting the crap.


----------



## PRC

bryceraisanen said:


> Not worried about the bar joist. Mostly the ductwork
> 
> Sent from my SM-G930T using Tapatalk


I should of been clearer, we term any metal industrial ceiling as "deck and joist" which includes all mechanicals in the ceiling too. And no we haven't solvent cleaned ductwork when using acrylic.


----------



## Stretch67

kmp said:


> The last one I did, and we used S/W dry fall, I etched the duct work. Didn't really have to but wanted to be safe.I only rinsed it once and the finish coat had weird blotchy spots. They went away after a touch up coat or two. I needed to rinse it twice. I used semi gloss dry fall and I might not have had the problem if I would have used flat.Exposed structural is such a dated look that I don't like and I really hate painting the crap.


That's exactly what I had in mind. With all the gyp below, a proper "rinse" is NOT practical. I think adding chemicals and water to the equation might almost be more recipe for disaster than just painting it the way it is

Sent from my SM-G930T using Tapatalk


----------



## Gwarel

I have seen guys wipe down the galvanized with vinegar to clean and etch. It is my understanding that some types of duct are suitable for painting as is and some need a vinegar wash. Sorry that I don't know more about how to tell the difference, but it is something to consider and do some research if your in that type of work.


----------



## DeanV

I did a residential exposed basement ceiling and the new galvanized did not like the acrylic dryfall. Adhesion was iffy.


----------



## CApainter

As long as a coating has a phosphitizing agent, like some water borne DTM's and galvanize primers do, acidic washing with vinegar doesn't seem necessary. Besides, vinegar will not remove oils. And that's usually the problem with ducting. At worst, and for newly installed ducting, a mild water soluble degreaser wipe and go rinse is all the prep needed with today's water borne DTM's. 

On the other hand, I've seen oil base and solvent epoxies literally shatter off of duct work due to their intolerance for expansion and contraction.


----------



## CK_68847

I always put some type of bonding primer on any type of duct work. I have seen dryfall fail on paint grip. If you are worried, the Bin oil primer will never fail. The Bin advanced is also very good. I usually use the ppg stain blocker bonding primer which also works fine. If you have sprinkler pipe, you should also spray it with an oil primer, so it don't rust.


----------



## kmp

I don't prime sprinkler pipe because around here it is coated so rust is not a problem, but I always oil prime the cast iron nipple at the sprinkler head because they rust badly.


----------

