Happy Holidays to all you lampworkers out there!
I still get many requests for what is a perfect 104 COE clear for lampworkers. I have found that it doesn’t matter so much who makes the clear glass rods as much as it matters if the rods are clean or not. Since I haven’t found any household cleaners that take off all the crud that can attach itself to glass rods, I decided to test the pickling technique that I learned about from bead maker Larry Scott.
The pickling compound comes out of the metal smithing trade and is used to remove surface oxidation and flux from silver, gold, copper and most other nonferrous metals after soldering or casting. The pickle also removes oxides and other crud off of glass rods with amazing efficiency. The pickling compound contains sodium bisulfate which is a stable form of sulphuric acid. This is gradually released into a water bath which keeps the pickling solution working for a long time.
Most people throw the pickling bath out after it has gotten really dirty. When you throw the pickling solution away, it is a good idea to throw some baking soda into the pickle to neutralize any acid that might still be active.
This pickling technique works best if the pickling bath is heated to 140 degrees Fahrenheit which is the temperature of a hot coffee. I bought a hot plate that has two burners on it, so that I could place a long Pyrex casserole pan on both burners to get even heating of the pickling solution. The casserole pan is long enough to place 13 inch glass rods in and have them covered with the solution.
I used to think you needed to use the pickle at ½ the strength that is necessary to pickle a metal project, but I found that using the pickle at ¼ strength worked well. It only took about 15 minutes of pickling to remove all the crud and leave the glass rods sparklingly clean.
I use a bamboo tool (wood or plastic would work also) to fish the pickled rods out of the bath (I wear plastic gloves when I do this) and I thoroughly rinse the pickling solution off the clean rods and stand them up on end over an absorbent rag or paper towel, so the water rolls off. You can wipe the rods off with a paper towel if you are in a hurry, but if you are cleaning a lot of glass it is easier to stand them up to drain.
As for safety, I wear an old shirt and an apron when I am pickling glass rods because little droplets of the pickling solution can get on your clothing and make little holes in your clothing. Wearing protective gloves when you are handling the pickle is a good idea and I use latex exam gloves because I have good dexterity for handling the wet glass rods.
It is a good idea to wipe down your pickled clear glass rods with alcohol just before you are going to use them which will remove any dust and finger oil that might have gotten on your rods after they were pickled.
I wondered if it was important to wear a vapor mask while working with the hot pickling solution, but I found out that it is not necessary to do so because the sulphuric acid is in a stable form and is not being released into the air.
There are two other elements to the equation for a perfect clear encasement on a glass bead. The first thing you must do is have the correct kind of torch flame to work the clear glass in. The best flame setting is a flame with a lot of oxygen in it which is a flame that has very short blue candles by the mouth of the torch. 104 COE clear glasses will develop soot on the surface from too much propane in the flame. The second thing you need to do to keep your clear glass encasement clean in the flame, is to keep your bead or sculpture at least 3 to 4 inches away from the mouth of your torch. I know this is hard to remember to do, but working too close to the mouth of the torch is a very hot area and will produce boiling and soot on your clear encasement if you drift into that area of the torch flame.
Encase you don’t know where to obtain some pickling compound, here is a link to where I found it: Click Here.
Through my experimenting, I have found that it is a good idea to pickle all your glass rods to keep from running into a dirty rod here and there while you are working. Pickling all the transparent rods is a given, but there can be dirt and oxides on opaque rods also and that is why I say to pickle all the different colors of glass rods.
I am super happy with the results of my pickling experiment and I hope you will give this technique a try, I wish I had a long time ago. For sure, I am going to be pickling all my glass rods from now on!