Summary for painting galvanized pipe Discussion
Painting galvanized pipe usually starts with thorough cleaning, then a primer that will bond to zinc. In the thread, an earlier visitor said scrub brushing with trisodium phosphate (TSP) and then using a self-etching primer handled consumer prep. Ted Mooney added that for manufactured parts, the best practice is to avoid chromating after galvanizing and instead use zinc phosphating followed by immediate painting. When Muhammad Shafique asked about a sandblasted galvanized pipe repair on a submarine, Ted said the preferred method is still a zinc phosphatization pretreatment line; if that is not possible in the field, scrub with detergent such as TSP, rinse, wipe with diluted vinegar, and then apply a self-etching latex primer. The discussion emphasizes that proper pretreatment matters most for adhesion, and that field repairs use a practical fallback rather than the ideal industrial process.
Q. How do you prep and paint galvanized pipe?
Joel W Parham
– Gainesville, Texas
2002
2002
A. An earlier visitor to the site reported that cleaning with a scrub brush
⇦ on
eBay or
Amazon [affil link] and trisodium phosphate
⇦ on
or
Amazon [affil link]
took care of the prep work. Then you just paint it with a
Self-etching primer
⇦ on
eBay or
Amazon [affil link]
. This assumes you are talking about a consumer application! A manufacturer who is making painted galvanized pipe should be careful to make sure that the pipe is not chromated after galvanizing, but is zinc phosphated and immediately painted instead. Visit www.galvanizeit.org to learn more.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
Q. I have already purchased galvanized pipe. Can I now paint it? If so, do I use Rust oleum? On separate occasions, both at Lowes and Home Depot, I have been told that I could and told that I couldn’t. .
. thanks muchly for your answer
Philip browning
– auburn, alabama
2007
A. The reason you get conflicting answers, Philip, is that painting galvanized materials is a difficult problem but no one is going to say it’s impossible, because it’s not; plus no one can say what’s
“good enough” for you.
If you are selling a product made from this galvanized pipe it’s one thing; if you’re just trying to scrape by with a personal project, it’s another. But for personal use get a primer made for the application like
Bulldog adhesion promoter
⇦ on
eBay or
Amazon [affil link]
and you should be okay. Good luck!
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
2007
Q. I want to ask how can we apply paint on galvanized pipe little mistake we done sand blasting on it. Tell me correct way to apply paint on pipe with preparation on submarine.
muhammad shafique
q c inspector – Karachi Pakistan
September 26, 2012
A. Hi Muhammad.
The “right” way to paint most galvanized surfaces is to first send them through a zinc phosphatization pretreatment line. Where this is not possible, for example on fieldwork repairs, scrubbing the area with a detergent like TSP, rinsing it, wiping it with diluted vinegar
⇦ in bulk on
or
Amazon [affil link] , then priming with a self-etching latex primer is probably the way to go.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
Q. This is reg. GI welded mesh painting:
After applying Etch primer over GI mesh, what is the maximum time frame within which the etched area needs to be covered with epoxy primer?
Heena Mehta
– Chennai, Tamil nadu, India
July 23, 2018
A. Galvanized substrates that not intended to be painted are usually passivized. You need to remove this thin layer of passivization before you can paint over it.
We occasionally get passivized coils, usually from one of our customers for a price to good to be true. A quick pass through the EG line removes the passivization before we paint.
Ronald Zeeman
Coil Coating – Brampton, Ontario, Canada
September 13, 2018
Q. Dear Sir, I want to paint Newly installed GI pipes for sprinkler system. First I am going to rub with sandpaper (hard) or clean with thinner; and then I apply zinc dust
⇦ on
eBay or
Amazon [affil link]
; and then final coat. Will in this way the pipes stay without peeling of the paint? Please explain.
feroz khan pathan
– MALANPUR INDUSTRIAL AREA
February 8, 2019
Q. I have to paint 2″, 4″ and 6″ thick GI pipes in children’s playing area. I have seen the answers on how to prepare and apply a primer. My question is about application of paint. What is better; application with a brush or spray painting?
RAGHVINDER JOSHI
Housing Society Management akin to House Owners Association – Mumbai, India
December 20, 2019
Q. No significant difference except perhaps in texture of the finish, and that dependent on the thickness (viscosity) of the paint at application.
If the paint is quite fluid, then brush painting should flow OK leaving a uniform coat without significant brush marks. User ability (skill) is required in how to brush the surface to minimize brushing marks.
Spraying might give a better finish, but also requires operator skill. Overspray can cause runs where excess is applied, and undercoating (thin) is easier to do my mistake in spraying.
If finish is critical, then consider multiple coat system.
Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK
January 24, 2020
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