Printable PDF Tip & Tricks booklet.
Using a Button and Knob Mold
There are two methods of using the Button and Knob Mold. The easier method is to first start by setting the mold on the table with the profile you want to use facing up. Shim underneath the handle if the mold is not laying flat on the table. Then heat a symmetrical blob of glass on the end of a glass rod. Bring the glass blob over the mold profile, with the rod perpendicular to the table. Let the blob barley stretch away from the rod just enough to help the molten glass to become a little better shape. This stretch needs to be very little. If the glass is very hot and you stretch it too much, the glass will get away from you and you will need to remelt it back into shape. Now bring the molten glass blob to the bottom of the profile, as close to center as you can, and push the rod down. This drives the molten glass outward, towards the rim of the profile. If it is not filling the cavity equally in all areas, you can steer the advancing glass with the rod as it is being pushed down. The glass that you see in the mold is the back of the button or knob. It will look like a bagel surrounding the glass rod.
It will take you a few attempts to develop the intuition of how much glass to melt. The first time the molten glass is pressed into the mold it cools and sets its shape fairly quickly, almost always before you get the glass to flow to where you want it. This is not a big deal, because you also unlikely have melted an incorrect amount of glass and will need to remelt it again anyway. The next time you push the glass into the mold you will find that you have more working time, because the graphite is hotter. It doesn't cool the glass as fast. As the graphite gets hotter and hotter, the more working time you will have. You can, of course, preheat the graphite in the flame, but do so very carefully at a low heat. Graphite disintegrates at high heat. You will weaken it and lose detail.
When you are happy with the formed glass, pull it from the mold. The glass rod is now a punty. Decorate the face of the button or knob as desired either before or after the back of the button is completed. This depends on your style of working as well as how you want the back to be made. The rod can be melted or nipped away. You can insert a metal loop into the heated glass (attach punty to the front first), glue an aftermarket metal loop on after it cools, or make a glass loop using a tungsten rod and or Peters Tweezers.
When you heat the back, center of the button with a regular, neutral flame, you will find that often the edge of the button becomes soft and will distort before you are done working on the center area. This can be prevented by using an oxidation flame. Increasing the oxygen will do this, but reducing the fuel gas will also do it and make a smaller flame than increasing the oxygen. Do whichever gives you the size flame that works best for the situation. This oxidation flame pinpoints the heat at the tip of the flame and the excess oxygen keeps the glass area outside the point of flame contact from getting too hot.
The second method of using the mold is very similar. The difference being, as you are pressing the molten glass into the mold profile, you are also rotating the glass rod and pressing the glass down with a paddle as it rises above the edge of the mold. Like described above, the mold cools the glass, but now so does the paddle. Until they both get hot, working time is even shorter. This procedure is to make the back of the button flatter and have a crisper edge on the back. This method takes more practice to make the paddled area not look so choppy from paddle marks. It is all about holding the paddle parallel to the mold as you pat the glass, having the correct amount glass (the other method is more forgiving on having an exact amount of glass) and having enough heat in the glass and in the graphite to give you enough working time to get it done before the glass cools.
Yes, this all sounds like a lot to do and think all at one time. Just as it did to learn how to spin a mandrel without holding your breath, it really takes very little practice, especially for using the first method.