Chalking of steelwork
Chalking of steelwork
(OP)
Hi All,
I have been contacted for technical advice on a coastal/beach development in Dubai (UAE, Middle East). The existing top coating of the external steelwork has been affected by the "chalking" phenomenon (see attached pictures).
The paint system has been specified by the Client as follows:
- Preparation, Grit bast clean to BS 7079,
- Primer. Zinc-rich Epoxy primer (60 microns DFT min)
- Build and finish coats. High build epoxy micaceous iron oxide (MIO) (min 200mirons DFT)
- Finish coat: Acrylic Polyurethane (60 microns DFT)
Do you have any experience with "chalking"? Causes and mitigation measures? Do you believe the specified paint specs mentioned above are suitable to an aggressive beach environment exposed to direct sunlight? if not, why?
Thanks
Regards
Simone
I have been contacted for technical advice on a coastal/beach development in Dubai (UAE, Middle East). The existing top coating of the external steelwork has been affected by the "chalking" phenomenon (see attached pictures).
The paint system has been specified by the Client as follows:
- Preparation, Grit bast clean to BS 7079,
- Primer. Zinc-rich Epoxy primer (60 microns DFT min)
- Build and finish coats. High build epoxy micaceous iron oxide (MIO) (min 200mirons DFT)
- Finish coat: Acrylic Polyurethane (60 microns DFT)
Do you have any experience with "chalking"? Causes and mitigation measures? Do you believe the specified paint specs mentioned above are suitable to an aggressive beach environment exposed to direct sunlight? if not, why?
Thanks
Regards
Simone
RE: Chalking of steelwork
RE: Chalking of steelwork
RE: Chalking of steelwork
Steve Jones
Corrosion Management Consultant
http://www.linkedin.com/pub/8/83b/b04
All answers are personal opinions only and are in no way connected with any employer.
RE: Chalking of steelwork
Steve is correct. I would recommend an acrylic aliphatic polyisocyante. Acrylics have excellent UV & Gloss retention. 2 urethanes our facility uses is Rustoleum 9800 & Gulf Coast Paint CT-398. Both products have over 3500 hours in the QUV which shows the weathering effect on coatings.
Thanks,
Andy