# Prep. and dry fall application



## Gordon Willingham (Feb 29, 2008)

I never have applied dry fall.
My question is mainly about prep.

My substrate is painted metal ceiling, painted metal trusses, painted conduit and pipes and wires. These surfaces have been painted and have been collecting dust for 20 or 30 years. In order to clean by hand all surfaces in this huge area it would take untold man hours, thus real expensive.

I am wondering if dry fall coating is more forgiving in this situation and considering that after application it will never be touched again.

Any guidance appreciated!

Thank you,
Gordon:thumbsup:


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## timhag (Sep 30, 2007)

All surfaces to be coated must be clean and free of dust, dirt, chalk, grease, oil,
wax, loose paint, form oils, and any other contaminates that would be detrimental to
proper adhesion. Remove all loose, scaly paint by sanding thoroughly. Surface
chalk must be removed by scrubbing with warm soapy water and thoroughly rinsing.
Glossy surfaces must be dulled by thoroughly sanding with steel wool. Any exposed
substrate should be spot primed with the appropriate primer.
Primers –
Steel – Metal Primers: 35-111 or 2090
Non-Ferrous Metal: 100-10 Perma Bond Primer
Wood – C37-11 Undercoater
Concrete Block – C946-11 Latex Block Filler
Poured Concrete – 4190 Latex Primer
New Galvanized Metal– 36 – 11 or 180-11
Aged Galvanized Metal – May be applied directly to properly aged galvanized​metal

http://www.olearypaint.com/architect_source/tab%206/documents/500251022902.pdf


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## timhag (Sep 30, 2007)

Oh.....Welcome to the site Gordon.


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## cole191919 (Jan 10, 2008)

No paint will ever adhere properly to surfaces with dust on it, never mind collected dust for 30 years. If at all possible, pressure wash. Will be a lot faster than cleaning by hand, and then you will know you have a much better surface to work with.


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## Joewho (Apr 17, 2007)

If it's just not possible to clean all the surfaces, try to get hold of an air compressor and blow the dust off first. Dryfall would probably be the first choice even if the surfaces were clean. As far as more forgiving, who knows. It dries as it falls through the air, but it goes on the surfaces wet, like any other paint.

Your situation is not uncommon. Happens like that all the time.


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## Housepainter (Jan 6, 2008)

I have not used it before but had a potential client ask about using dryfall. Is this a good product to use in a basement area in the overhead rafters, etc. I also noticed in Tim's "link post" that humidity can make a difference in dry time on the overspray. This areas is fairly humid (Gulf Coast).


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## YubaPaintPro (Mar 2, 2008)

Gordon, welcome. I'm new as well and learning the "protocol" here. All the guys are correct. Really the major benefit to "dryfall's" is that most dry by 18-25'. Adhesion can be enhanced by using an oil vs latex. And like th listed, even oils don't stick well to dust.

Not sure where you are in L, however we have stores in TX(San A, Big D) that may be able to get you material. Kind of a long shot though.

One product that acts like a dryfall, is Noxyde. It is spec'd for many CA bridges and is manufactured by Mathys/Rustoleum. The material is amazing. I won't screw it up by trying to hard to explain it fully, but is has elastomeric properties, dryfall properties, and encapsulates loose scale rust. I have sprayed it through a SprayTech 2155 electric rig, w/ a 413 flat tip. I put a 5g stir stick in the bucket while spraying and it stood tall in the bucket w/o falling over. Can be a finish coat in this situation for sure, but in high traffic areas an epoxy, DTM is my recommendation. Noxyde is a pretty penny, but the prep for "rust" jobs it is very worth the cost vs the prep costs.


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## [email protected] (Mar 1, 2008)

We have used it many times for ceiling rafter.
David Enterprises


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## paintboy2 (Mar 8, 2008)

For existing buildings/re-paints, most painters typically blow down with air. In most cases it isn't practical to clean a ceiling by wiping down. It's typically not safe to power-wash due to electrical. There are other considerations when cleaning in occupied areas, dust and water can damage equipment. Make sure everything is covered with plastic.

For new construction beware of rust on primed steel. For rusty substrates apply an alkyd dryfall. Other than cleaning footprints, due to contractors walking on during construction, and cleaning weld spatter there is really no surface prep required for most new construction dryfall projects.

Galvanized metal may require washing with an etching cleaner containing phosphoric acid prior to painting. Tubular steel/duct work have passivators that won't allow paint to adhere properly. These oils must be removed prior to painting. Never use alkyd products on bare galvanized (gauranteed paint failure).

Pre-primed decks - There are some primers that are used in coil-coated applications that are being used to achieve LEED or Green-Seal certification. These products are becoming more common, and are probably more the rule than the exception in construction nowadays. As of now paint manufacturers will not recommend coating these decks with water-based material. They won't stick properly and tend to crawl and fish-eye. Use alkyd paints. 

These recommendations are not textbook but are generally accepted in the field. If you were to do what was recommended by the paint manufacturers, you would never get a project like this because you wouldn't be competitively priced.

I would recommend contacting your paint supplier for a couple of projects to assist with recommending the proper preparation and coating for the job.


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## Charles G (Aug 6, 2021)

The best product to use if there’s any rust at all, is Sherwin-Williams KEMBOND oil based, high bonding metal primer. (Can be sprayed.) Then over that, DTM for the topcoat paint

dryfall is honestly cheap and adequate, but not that great. If you want a longer lasting quality job, use KEMBOND oil primer+ DTM topcoat


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## CatJP (Jun 28, 2021)

I have used both oil and latex dryfall. Mostly in factory areas. I recommend blowing off as much dirt/dust as you can then spraying the dryfall. The oil is more forgiving and will hide more oil or water stains. The latex will look good at first, but will yellow as it dries if there are oil or water stains. Not sure how high your ceiling is, but if less then 18' I would cover what is below. Moister will cause the latex dryfall to stick to anything damp. Ran into that problem before. Hope that helps


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