Black Phosphate

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  #1  
Old 07-10-03, 10:22 PM
H
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Black Phosphate

Those drywall - Black Phosphate screws-
are they considered rust/corrosion proof?
 
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Old 07-11-03, 05:25 PM
NutAndBoltKing
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In the most general of terms - yes, but the degree of resistance mostly depends on the thickness and hardness of the coating, which varies among the manufacturers - and now more recently can be easily be determined by where those makers are located.

Presently the US is being flooded by Asian products which quite frankly do not meet the performance standards we've become accustomed to. They LOOK okay - but users experience snap, rust, and head strip out. I won't stock or sell them. IMHO: That "Most Favored Nation" status given to a country by the folks in Washington just inundates our market with lots of junk and puts hard working people on the unemployment line.

In an effort to combat the purchase of cheap substandard imported products US and Canadian manufacturers are printing detailed box labels and packaging their products with info sheets explaining the benefits of their base materials, processes, and coatings.

Look for where the screws are made, buy US or Canadian, and look for the word rustproof on the box or package.
 
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Old 07-11-03, 08:57 PM
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handyhand,

Your answer is this....the screws are made with a liquid concentrate which is diluted with water and used as a black pre-dip prior to zinc phosphating steel with an EPI E-Phos phosphating solution. The black pre-dip becomes an integral part of the phosphate coating and will not rub off.

The oil absorptive zinc finish is an excellent base for the retention of an EPI E-Tec corrosion inhibitor which will provide a highly corrosion resistant black finish.

NutAndBoltKing said it right, be careful when you buy the products. Just looking at a box through the clear plastic isn't enough anymore! Alot of packaging looks familiar until you read it and the standards are meeting ASTM requirements.

Just some thoughts!
 
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Old 07-12-03, 08:56 AM
NutAndBoltKing
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Doug's description of the process is excellent, and I'm happy to report that drywall screw companies are constantly making improvements to the tensile, yield, shear, and pullout strengths of their screws and are alway improving their rust, corrosion, and hydrogen embrittlement resistance. It's not obvious to everyday users mostly concerned with size and length and maybe TPI, but drywall screws have improved a great deal. Nearly all drywall screws produced by North American companies exceed established standards. Visiting screw salesmen have always given me great info packets and samples, but now they also leave short videos showing their production process and product testing methods and results.
 
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Old 07-14-03, 09:26 AM
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thanks for your expertise.
from experience I agree with the king on the inferiority of non-USA fasteners. you get what you paid for- Quality Assurance costs money.

I was having a hard time finding a 1" underlayment screw(cement boards). (I dont need the 1 1/4") I was only able to find the 1" size for drywall applications- I could not find them for exterior applications either (hot galvanized/decks.)
 
 

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