Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Prepare the steel before galvanizing
Q. for black shaft steel poles, is it a good option to make it brushed finishing before galvanizing?
Alex lau- jiangsu, china
December 19, 2019
A. Hi Alex. I am not familiar with the phrase "black shaft steel poles" but, from googling, it seems to mean hot rolled or hot finished steel poles (in other words, not cold finished).
The surface can be brushed before galvanizing, but I don't think you would see the brush pattern after hot dip galvanizing -- perhaps your concern is only whether brushing can be used as a pretreatment, and you're not looking for the aesthetics of the brushing to show through; in that case I think it's probably fine. Sweep blasting, as described in thread 50341 may or may not be more practical for your situation. Hopefully some galvanizers will answer your query too.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
December 2019
Q. Hi, thank you Ted,
Yes, it is hot rolled steel. square pole or round pole. We now starting some business with steel fence poles.
About the brushed finishing, or we call it satin finish? Use the grinding disc to polish the surface.
What I understand, or imagine is, the surface is more polished, the impact area will be more and smooth, which will have a better effect with all the chemical liquid and melted zinc :)
Alex
- jiangsu, china
December 20, 2019
A. Sorry, I don't have the hot dip galvanizing experience to be able to answer that, and I don't even know quite what you have in mind by "better effect". But we do have readers who may understand you better and who may be able to comment on the proposition.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
December 2019
A. Almost any surface treatment prior to galvanizing will increase zinc consumption and resultant coating thickness. Unless you actually want thicker coatings (lasts longer but costs more), then it is not advisable. Any grinding, brushing or blasting that re-profiles the surface will have this effect.
If you have a set price with your galvanizer, they would be not pleased that you started doing this, as they would use more zinc to do you work.
There's no process benefit, only increased cost.
Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK
January 7, 2020
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