Fluxing after hot dip

A. I understand from another question that you can do it while spraying Ammonium Chloride or Sink ammonium Chloride. I tried that yesterday but it disturbed the skimming process. At some products you need to skim constantly while lifting the product out of the bath. Now I hear that you can have same result with hot air, anyone familiar with that? Ed Ploeg - Bocholt, Belgium A. Some people just use flux solution in a spray gun to do this job. Sometimes it works. Geoff Crowley Crithwood Ltd. Westfield, Scotland, UK

A. The problem you are describing can be caused from several things. If your overall appearance is good, and the coating thickness is not excessive, then I would look at three things. 1) Is the material properly fabricated for galvanizing? In the case of fabricated pipe, tubing, tanks, corners in structures that will hold zinc, etc., proper venting has to be done to allow the zinc to freely flow out. 2)The hoist speed is critical for drainage (and I think all overall appearance). I would recommend no more that 4 feet per minute (I prefer 2). 3) Technique. Your kettle operators will make all the difference. A lot of material may require stopping on the way out at various points to allow time for a section to drain before continuing. A good example would be a ladder made of pipe with steps made of pipe. Even properly vented, stopping on the way up may be necessary at each step, if only for a few seconds, to allow the zinc to drain before going on, can mean the difference between a smooth finish and one that had excess zinc from improper drainage at each step.

In summary, proper venting, kettle speed, and well trained operators will always minimize drips and excess buildup.