In my column for December 2001, I outlined some possible paint stripping solutions for R.R. After that column I received two more suggestions regarding hooks and racks. In the first comment, I am not sure how the metal would lose its ground with a burn off, but the writer does bring up a good point regarding the rated weight capacity. Depending on the base material of the hook, the burn off time and temperature, it is very possible that the hook will not have the same load capacity that it came in at considering that the base material could go through stress relieving or even annealing. The mechanical properties of most metals would dictate that the material will get “softer” (lower tensile and yield properties) and more ductile when exposed to a stress relieving or annealing process. Despite this, I have seen many people reuse the hooks and racks, if designed well in the beginning, for a very long time. The decision should come down to a monetary comparison of the cost of a burn off oven (with occasional hook and rack replacement) versus very frequent hook and rack replacement.
In your December Q/A page, you had an inquiry regarding the stripping of used hooks and racks. We are one of the largest producers of hooks for finishing systems in the world. We have found that burning off hooks does significantly reduce their weight capacity and can even prevent the hook from carrying a ground. Instead of suggesting to our customers that they try to reuse hooks, we make the hooks economic enough to be thrown away after one or two uses. This not only guarantees the safety of the operator and product and increases powder transfer efficiency but also ends up costing them less in the long run.
In the second comment, the writer indicates that there is a new type of rack cover or cap that is made from a conductive silicon that can be fitted over the existing hook. After painting, it can be removed and replaced with another one. This could be a third alternative in the monetary comparison suggested above. Since silicon rubber is not inexpensive, you would have to consider its life and replacement cost.
Dear Mr. Peterson:
I wanted to bring to your attention another alternative to current rack and hook cleaning methods that wasn’t mentioned in your response to R.R.’s question on pp. 36 and 37 of the December issue—conductive hook covers.
We received patent approval in early December for the highly conductive, pliable silicon coverings. These covers slide over the ends of hooks allowing good ground to be maintained and protecting the contact point of the hook or rack from buildup. After a predetermined number of runs (usually more than achieved from bare wire), the used cap can be easily removed and replaced with a clean cap. It’s a cleaner, simpler, more energy efficient and cost-effective alternative to the other options you mentioned.
We felt that a person in your position should be informed that this product is out there on the market, and customers have been very pleased with its results. It’s a very innovative product and is being embraced by a number of large corporations in both the U.S. and Canada.