The authoritative public forum
  for Metal Finishing since 1989
-----

What's the weight of the thickness?

What formula would I use to figure out the weight of the Silver need to plate both sides of a disc 15 inches in diameter and .375 inches thick? I work for a manufacturing company and have had a large disparity of pricing for this job and the vendors say it is the cost on the silver.

George Verhoest
- Fairfield, New Jersey
2007

---

That would be the surface area of the part times the thickness of the plating times the density of the plating (this assumes the silver plating is relatively thin and does not appreciably increase the surface area of the part after plating).

James Totter, CEF
- Tallahassee, Florida
2007

---

2007

Area x thickness of plating = volume of plating,
volume of plating x density of metal plating = weight of plating

Presuming the circumference is also plated (otherwise, why mention the disk height of 0.375")
Area = pi x (Radius squared) x 2 + pi x Diameter x height = 371.1 sq. inches

Need the plating thickness. Using the 0.0005" minimum specified in QQ-S-365 for non-ferrous substrates, the volume of silver is 371.1 sq. in. x 0.0005" = 0.18555 cubic inch = 3.04 cubic centimeters (cc).
Density of silver is 10.49 grams/cc, so weight = 31.89 grams = 0.842 troy ounce.
About $11 worth of silver, or $22 per mil thickness.

You are welcome to buy 1-troy oz. of 99.9% silver on Amazon.com for $20 and try plating from it: Silver-Liberty-Proof
but you will encounter difficulties. Better to pay a plater having the right pretreatment & plating chemistry, expertise, equipment, environmental controls, etc., who certifies the work to the QQ or an AMS specification.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.

---

2007

Two points to add to the calculations
1/ The plating is not evenly distributed. The thickness will be greater near the edges. If you really need to know the weight of silver, a simple method is to weigh the part before and after plating.
2/ Although silver is still classed as a precious metal and gets accountants excited, It is not in the same cost class as gold and platinum. The greater part of the cost is in the labour and overheads in plating it and the plater is entitled to make some operating profit.

It is a general rule of commerce that the selling price of a commodity is what a buyer is willing to pay. This often has little connection to the material price. What do you think the cost of bottled water ought to be?

Geoff Smith
Hampshire, England