# Acrylic/Latex vs. Alkyd/Oil For DTM. Is Acrylic to be Trusted?



## TomBrooklyn (Dec 15, 2008)

I don't trust acrylic paints for direct to metal applications. Expecially for exterior work, or anyplace that has or may come into contact with water, or any metal that already has some rust on it. 

Am I too old fashioned?


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## bikerboy (Sep 16, 2007)

TomBrooklyn said:


> I don't trust acrylic paints for direct to metal applications. Expecially for exterior work, or anyplace that has or may come into contact with water, or any metal that already has some rust on it.
> 
> Am I too old fashioned?


Would not go over rust, but otherwise like the acrylics.


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## NACE (May 16, 2008)

Alkyd DTM's have better wetting properties on marginally prepared surfaces and are less suseptable to flash rusting. Better adhesion to poorly prepared surfaces too. They do have very good rust inhibition since oils tend to be less pourous than latex/acrylic due to the way the film forms and the slower dry times. Very good rust inhibition on tight adhering rust. Oils have better chemical and abraision resistance for the most part. They do tend to break down and chalk in the presence of UV, loose gloss and color more quickly as well. Acrylic DTM's have very good gloss and color retention, quick dry times and recoat, and have very good rust inhibition over surfaces that are clean and abraded to clean or bright metal. They also perform better in humid conditions and can be put back into service quicker, have less odor during application. Acrylics have almost equal to hardness as oils, cure slower, but remain tight and hard, as oils continue to oxidize throughout there life and become more brittle, compromising future topcoats. Most acrylics are resistant to most epoxy and urethanes, or coatings with hot solvents. Alkyds, are not resistant to hot solvents. Most alkyd DTM's, unless a phenolic resin is used, can not be put on galvanized metal. Supponification or zinc soap will be the result. Really depends on the scope, spec, environment and conditions which determines where one over the other will be used. We just completed a 280,000 sq ft dual hockey rink in which the ceiling was shop primed structural steel trusses and beams, with a insulated galvanzied roof deck. We sprayed the ferrous metal with Universal Metal Primer, which is a phenolic alkyd, so any over spray on the galvy would not be compromised. We finished everything with an acrylic DTM semi gloss. Surface temp, humidity and dew point were all a factor, however we had minimal flash rusting on lower sections that could not be sprayed with Universal Primer, and just had 2 coats of DTM Acrylic over shop primed steel that had been exposed outside for at least six months. Prep was SSPC-SP-1, and SSPC-SP-3. Looks great.


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