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Topic: Guidance  (Read 1090 times)
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« on: April 10, 2012 07:21:11 AM »

I generally work with metal...
A friend gifted me with a kiln (Delphi EZ-PRO) which I've used for PMC stuff.
She also gave me a bunch of molds for glass slumping...some smaller ones for jewelry pieces and larger ones for plates and bowls and stuff.
I have no idea at all what to do or where to go look for stuff....the tag on some of the molds indicated purchase from Slumpys so I have gone to that site a little but I'm overwhelmed with not knowing.
Glass isn't the medium I work in but I think it would be a waste not to dabble a little bit with so much stuff already invested in for it....
Any guidance on an idiot's guide to this realm?
What would I absolutely have to purchase? 
Where can I find affordable stuff?
Any advice is appreciated Smiley
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« Reply #1 on: April 10, 2012 10:23:06 AM »

Hi and welcome! Smiley

Before you proceed I must warn you, glass is very addicting!  Grin

Since I do not do slumping I will paste a post by one of our glass mavens, CrazyEyeGlass, who does that kind of work. You will find a lot of great info, but should you have more questions, please let us know.

My favorite online resource is glass-fusing-made-easy.com. Here's a link to their bit on molds: http://www.glass-fusing-made-easy.com/molds.html


Some slump molds are more challenging than others and you'll even see them rated in some stores with beginner to expert ratings. Anything that strays from simple geometric shapes, such as the half circle shape you mentioned, will be more challenging.

The easiest way to get the right size and shape of glass for the mold you want to use is to invert the mold onto the glass you want to use and trace the edges of the mold onto the glass with a sharpie (remember to clean the glass before firing). Of course there are other ways to do this, such as simply measuring the mold from tip to tip and cutting the glass to exactly the same measurements. Basically, you do not want any glass to overhang the edges of the mold. If the glass does overhang the mold, you run the risk of trapping the mold in the glass and ruining both your project and the mold. Once the glass is cut and you've done your initial full fuse, recheck the size of the fused glass against the slumping mold--chances are the glass has "shrunk up" a little, but it may be slightly larger after fusing depending on how many layers of glass you've applied. If the glass has shrunk up evenly, no problem! It will still fit within the slumping mold. However, if the fused glass is now larger than the slumping mold, you'll have to repeat the steps above with a sharpie and use a grinder or ring saw to get back to the correct size.


Lots trickier than slumping! I don't have a lot of experience with draping, but have done a little (my kiln is fairly shallow, so I can't do any dramatic draping). Draping requires a lot of experimentation. When measuring the draping mold, you want to use a tape measure (whatever tape measure you use--cloth, metal, ruler--do yourself a favor and use the *same* tape measure for your entire project--there are always slight differences between tape measures and if you don't use the same tape measure you will begin to question your sanity) to measure from the surface vertically to the first high point, then up over the top and back down. This will give you the basic measurement; you need to shorten up the measurements when you cut your glass since you don't want the edges of the glass to drape onto the kiln floor/kiln shelf and possibly puddle there. Draping round pieces is easier than draping rectangular or square pieces.

As for balancing, this is very difficult indeed and why it's an advanced technique. You could try placing a small piece of thick fiber paper on the high point to give yourself a slightly more stable area to balance the glass.

If you still have questions about either slumping or draping, let me know and maybe I can gin up some youtube videos in the not too distant future.

As for finding the items at reasonable prices, check this thread.

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« Reply #2 on: April 10, 2012 11:21:56 AM »

Thank you!!

I guess I feel I have lots of crazy simple questions...like I've gathered that for the earring style molds I should use frit in the molds...can I mix colors of frit to get other colors? Will mixed frit just end up mottled and cool?

I'm far more comfortable starting with the small stuff before even attempting slumping anything on the huge bowl molds...I wish I knew someone half-local who could give me a quick and dirty lesson Smiley
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« Reply #3 on: April 10, 2012 02:01:21 PM »

If you mix the frit in the mold it will be mottled. Test it with a few and you will get the feel for how the glasses react. Smiley

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« Reply #4 on: April 10, 2012 03:27:37 PM »

Try using one color of frit in your mold at first to get a feel for using it. Mixing translucent colors (see below for how to tell if your frit is translucent or opalescent) will make muddy colors.

If you're working with fine or powder frit, I strongly recommend you use a dust mask or a respirator--you don't want to inhale frit!

Also, remember to coat all sides of the molds with kiln wash or the glass will fuse to the mold!

There several sizes of frit--coarse, medium, fine, and powder. Any time you fill a mold with frit, heap the mold up so the top is rounded, to account for any gaps or air space between the frit. The coarser the frit, the higher you have to pile the frit.

Another consideration with frit is opacity--some frit is translucent and some is opalescent. Bullseye's frits are marked with a color and a number. For example, if the number is 0113, the leading 0 means the frit is opalescent (a good mnemonic is 0=opal), and if the number starts 1113, that leading 1 means the frit is translucent. The rest of the number corresponds to the color in the catalog.

HSG is right! Glass is highly addictive! Enjoy, ask lots of questions, and post pix!

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« Reply #5 on: April 11, 2012 01:05:20 PM »

Welcome to glass! :-)

I'd also like to point out that all glass is not created equal... depending on the type of glass you get, it will have a different Coefficient of Expansion (COE) from other types. Using glass with different COEs together will result in your piece cracking, chipping and sometimes outright exploding in your kiln!

Basically, what happens is that the different types of glass expand and contact under heat at different rates. Meaning that a lot of strain is put on areas that are cooling and heating at different times, at the molecular level. And, while it may look at first like they have melded well together, they almost invariably separate over time, even if it can take a couple of years to do so.

But, do not panic! Here's a small rundown of the more common types of glass...

104 COE - very 'soft' glass i.e. it melts at a lower temperature and is very easy to manipulate when molten. This is the glass - normally sold in rods - that most non-Japanese bead makers and Lampworkers use. Japanese lampwork glass is even softer - from 112 COE up to 130 COE - but I've never actually seen any for sale!

96 COE - This is slightly harder glass that most stained glass makers use, and a number of fusers are using too. Normally sold in sheets, its also available in rods. While it doesn't seem to have the same problems with devitrification (a scummy dull surface left on some colors after firing), it also doesn't come in the same wonderful colors that either 104 COE or 90 COE (see below) come in.

90 COE - "Bullseye Compatible"  Is by far the most common type of glass used amongst fusers. Bullseye  - one of the biggest glass manufacturer - is also making a good selection of 90 COE rods now, so an increasing number of lamp workers are using it too.

Theres also the harder more specialist glass for things like marbles, pipes and pendants - Borosilicate - normally somewhere between 33 COE and 38 COE . It normally comes in rods and tubes, and rarely in sheets. Its very hard, in fact its commercial name is Pyrex - as in the ovenware - and needs special equipment to melt.

My advice would be to use 90 COE glass in whatever slumps or casts you decide to make with your newly acquired equipment. It comes in the best range of colors outside of the 104 COE range, in the most flexible of shapes and sizes, and the most stocked by glass suppliers.

Anyway, if you have any questions I'm sure that all the people here would be more than happy to answer them. Good luck and have fun!
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