Glass Fusing

@ What is your firing schedule and COE of glass you are using?

I'm using 96 Spectrum glass.

@Susan H. What COE are you working with?

I slumped a small deep bowl and the firing took the glass all the way to the bottom of the mold. However, it came out lop sided. I believe I can even it out but I'm not sure what firing schedule to use. The first firing was low and slow and had 8 segments. I might also mention that I first did a full fuse of the two pieces of glass and of the additional embellishments before doing the slump fuse. My fear is that all of the glass will slump into the bottom of the bowl. I'd appreciate any suggestions. Thanks so much.

@twillitespirit The rounded top is achieved when the glass is taken to a full fuse.

I'm curious on how to get a "domed" or r"ounded top" (looks like half a marble) like You see on earrings, on glass cabochons?

Based on your second description it sounds like it is too hot, single layers shrinking trying to get to a 1/4" thick. The temperature doesn t sound too hot though. The first one may have worked out ok because it was larger but really if the smaller pieces shrunk, the first one should have also. I don t know what the wrinkling on the surface is. Maybe the paint was thicker on the second firing? If the second fire was too hot maybe the shrinking caused the wrinkling around the paint?

@krisd This question is subjective and depends on the size of the project, the type of glass being used, what kiln is being used, etc. When I fuse I typically ramp up all projects except my jewelry cabochons at 200* F an hour. Whichout knowing what your kiln settings are for Fast, Medium and Slow that is harder to answer. The other part of this is that the end temperature is what really helps define the end results. A basic tack fuse is around 1340* F again, depending on your kiln it might be a bit lower or higher, it will take some trial and error to find the perfect temperature for each kiln.

The glass will actually all be the same thickness once fused. Glass likes to be 1/4" thick so it will shrink to make that happen. The edges and center will pull in equally to get to that magic number.

I'm tack fusing small panels, (4x7 90 coe) the bottom clear glass is 3mm, and I'm stacking a few pieces 1 to 3mm high. So in some parts, it is over 6 mm. I have it at a tack fuse 90 medium speed. (which is what is says on my Evenheat kiln preprogrammed) I usually do a tack fuse 90 fast speed, but since these are a bit thicker, I am using a medium speed. However, it seems it reached a high temp, faster than the "fast" speed would have. I'm hoping this will still be a tack fuse by the time its done. So, my question is, if I use more than 6 mm thickness, how should i tack fuse this? Fast, medium or slow?

@ Creating with a mold that has some texture and depth like this one can be a bit challenging. Our instructors would recommend that cutting 2 layers of glass and fusing them together in an initial firing, then placing the fused glass on the mold and slumping is going to be the most likely way to achieve good results. For slumping, you can use a fairly common schedule with a ramp rate of 200 degrees an hour, the key to getting depth and detail is going to be going to a slightly higher temperature than usual, around 1300 degrees F, but only holding at the top temperature for 5 to 10 minutes before cooling as fast as possible to your annealing soak. Happy fusing, and we sure hope you get a perfect pumpkin plate to enjoy this fall season!

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@curly6 The slightly matte or textured surface is the result of the glass touching the mold. Unfortunately, at the temperature needed to "fire polish" something, the glass is soft enough that it will not retain the slumped shape. For future projects, you can attempt to avoid this finish by reducing the time that the glass is exposed to slumping temperatures. You may wish to set an alarm on your controller for when the kiln reaches the target process temperature so you can check the slump progress and skip to the next (cooling) segment of your cycle. This may help prevent the glass from fully settling into the mold and imprinting the texture of the ceramic mold surface.

I just slumped a very nice 12 inch bowl. The inner surface and edges are smooth and glossy. The outer surface (that went down into the mold) is not looking good. Can I refire so the outer surface is "polished" without disrupting the rest of the bowl?

@bigdogpots There are no absolute ratios that will allow you to reduce the firing temperature and increase the hold time (or vice versa) to achieve a similar fused effect, and in this instance, our fusing instructors suggest that time and temperature are not the most likely culprits causing the devitrification. The first thing to consider or try changing is how you clean the glass before firing. Some glass needs to be exceptionally well cleaned because any oils or residue on the surface greatly increase the odds of devitrification. You can use denatured alcohol, vinegar, dish soap or glass cleaner to break up oils on the surface, scrub the glass well using a soft bristle brush or cleaning cloth, and rinse extremely thoroughly. Additionally, using glass that is tested compatible for fusing should cut the risk of devitrification. If you are using glass bottles, window glass or other non-tested glass, you may find that using a coating of Super Spray or Clear Coat Overglaze will help keep the surface glossy and smooth. I hope this helps you to get the perfect finish on your fused art.

Is there a formula or ratio to figure out achieving the same kilnforming effect at different target temps and hold durations? I have a project that appears have some slight devitrification and would like to avoid that in the future by heating to a lower target. In this case my target temperature was 1260 for .45. What would be the hold time if my target was 1220 to get the same effect?

@ I reviewed your questions with our fusing instructors to ensure I'm addressing all the potential issues. In reference to the devitrification, there are multiple factors that can impact that, not just the firing schedule. Using glass that is specifically tested compatible and formulated for fusing is the first step in getting a gorgeous finish. Beyond that, avoiding using a grinder is recommended as the residue from grinding can sometimes show up as a dingy looking halo. Additionally, when cleaning glass before fusing it is important to thoroughly rinse all cleaning agents off and wipe dry with a clean, lint-free cloth. If these factors are eliminated you stand the best chance of getting beautiful results. For your 1" - 3" cabochons a firing schedule of seg.1 500/h to 1000F with 5 min. hold, set.2 500/h to 1250F with 10-15 min. hold, seg.3 500/hr to 1450F with 10 min. hold, seg.4 Full/h to 900F with no soak/end program is appropriate. The hold at 1250F is commonly called a "bubble soak" and should be longer for larger projects or projects in which you wish to minimized bubble entrapment from textures, frit and more. We can't wait to see what you create!

@jsyorganic Making glass cabochons can be a quick, fun way to be creative. Due to the smaller project size, firing schedules can look a bit different from the schedule you would use for a larger project. Ramp rates can be a bit faster, and soak times are generally shorter or even removed from the schedule. Without reviewing the complete schedule you are referencing it's difficult to say if the omission of a soak time is correct, but I would anticipate that your projects should round out and be fully fused using a schedule with no soak at the peak process temperature.

Hi! I need an advice on the firing schedule. The size maybe 1-3 inches of jewelry cabochon glass stone with 6mm thick. I am curious about the full fuse schedule, segment 4. There is no soak time unlike other firing schedule. Is this correct?

@tiptondf While some artists are able to successfully fire glass in a ceramic kiln, it is a much more challenging process than fusing in a glass kiln. Glass kilns typically have elements in the lids that allow the glass to heat more evenly, whereas ceramic kilns often only have elements around the outside perimeter. Because of this difference, and the difference in firing chamber size it is important to be cautious not to heat or cool the kiln too quickly as the risk of thermal shock is greater in this configuration. Additionally, ceramic kilns are usually designed with a lot of depth for tall artworks and to allow multiple shelves to be stacked. While this is fine for ceramics, positioning multiple shelves for glass firing can create uneven heating and heat distribution. The result of this may be some projects over-firing while others are under-fired, as well as increased risk of thermal shock. To best determine how to use the built-in controller you may wish to reach out to the manufacturer or a ceramic supply business that is more familiar with the operation of the controller as it relates to heating rates in that particular model of kiln. Additionally, there are multiple types of pyrometric cones, and using them to gauge temperature isn't an absolute measure, as style of cones, heating rate and firing time can impact their performance. It appears most process temperatures for glass fusing can be achieved between a cone 019 and 013. You can find more information about cones by conducting a web search for pyrometric cone temperature charts. For more information about preferred glass firing schedules you can visit https://www.delphiglass.com/page/knowledgeBaseView?KBItemID=90

I just inherited an older Duncan kiln that uses cones I want to fuse answer slump glass in this as it is larger than my glass kiln. What cones do I use and how long does it need to fire there are 2 dials on kiln having low,med, and high

I just inherited an older Duncan kiln that uses cones I want to fuse answer slump glass in this as it is larger than my glass kiln. What cones do I use and how long does it need to fire there are 2 dials on kiln having low,med, and high

@ When slumping glass that has already been fired to create a 1/2" thick slab of 12" diameter, it will be very important to slow the ramp rate and include soak time on the ramp up to avoid thermal shock. The following is in degrees Fahrenheit. Try a schedule of ramp rate 150/hour to 1000 degrees, soak 30 minutes. 150/hour to process temperature (about 1275), soak 15 minutes. 999/hour to 900 degrees, soak 2-3 hours. 300/hour to 700 degrees then shut down and allow to cool fully to room temperature before removing the project from the kiln.

@nancyknuckey There are several reasons that air can be trapped and form a bubble in the center of your project. The most common is that the glass is being heated unevenly and the edges are becoming soft and sealing shut before the center softens. To help alleviate this, you can reduce the rate your kiln is heating at and add a "bubble squeeze" segment to your firing schedule. Another tactic some artist find useful is to position little chips of clear fusible glass (compatible with the project) at intervals around the outside edge to act like tent poles, creating a tiny gap on either side for air to escape during firing.

I am getting trapped air in the middle of the saucer/coaster mold. I am using 2 layered fully fused glass. Should I drill a hole in the middle?

@ There are a few common reasons that the glass may not have slumped as desired. The first factor is that although kiln controllers often include pre-set firing programs based on averages, each kiln can fire a little differently. The size of the firing chamber, the material the kiln is constructed from, and the calibration of the controller can all be factors. You may want to adjust the firing schedule to have a longer hold time at the top process temperature to allow the glass time to slump, or you may need to increase the top process temperature slightly.Another factor can be the shape of the mold and size and thickness of glass used. For some mold shapes it is ideal to slump glass that was initially fused in a dam mold, allowing you to create a glass piece that is thicker than the 1/4" average achieved by layering 2 pieces of glass. You may want to experiment and try using this slumping mold with 3 layers of glass to see if the extra material and weight help it to reach the full depth and shape of the form.Additionally, make sure the vent holes in the mold are not clogged with mold release. These tiny holes allow the air to escape so the glass can slump to fit the contour of the mold. Trapped air may prevent the glass from dropping, or can even cause bubbles to appear in your project.

@ The process of fusing relies on heating the glass to a semi-liquid state. Setting a lower process temperature to achieve just a tack fuse will allow you to maintain a fairly crisp square shape, however, if a contour fuse or full fuse is desired, the glass will be liquid enough that the corners will round and the glass will either pull-in or flow outward to achieve a depth (or thickness) of approximately 1/4". If you desire a full-fused look and a square shape your options are to use a mold or dams to contain glass to a square shape, or to coldwork the fused project.

@gatormichals you do need to make sure to remove ALL of the Primo Primer. You might try a dry scouring pad or light sand paper to make sure that all of the primer is removed. Nylon panty hose and paper grocery bag can also do the job effectively. We offer a new product that is replacing MR-97 - it's called ZYP - it's in stock now.

Please I need a fusing experts advise, I have a slumping mold I've coated with 4 coats of Primo primer kiln wash but I've decided I'd rather use MR-97 on the mold instead; I know I can remove the kiln wash by with water and a brush, I believe I have removed most of the kiln wash the mold has a slight purple color my question is, Do I need to make sure all of the kiln wash is removed before I can spray the mold with MR-97? If there is still a slight purple color that would indicate there is still some kiln wash residual correct? Is there any thing else I need to do before I can use the MR-97?

HI Jennifer, I am going to increase the time of the middle 40 minutes & leave everything else the same. IF this doesn't work I will give Delphi a call, wish me luck !

@cucabee your firing schedule appears to be a good one and I can't see any reason for it not to work for you. Perhaps your temperature gauge is wrong - all kilns vary a bit and this isn't entirely unusual. A solution for that can be simply experimenting with your target temperature (go a bit hotter) and hold times (hold a bit longer.) Another possible issue is that you are loosing heat out the bead door. A solution for that is to simply purchase a fiber blanket, cut it to fit the door, and use it to seal any gaps. If you are using dichroic or iridized glass the edges sometimes don't melt as smoothly as regular glass due to the coating - that could also be a part of the problem. If you continue to have issues please feel free to give our customer service department a call. We are here to help you be successful and enjoy your glass art!

@blaqsmoke you could certainly buy two and put them together to get the length but you will likely have a seam. If you try it I would definitely recommend some fiber paper at the seam.

Hello, I have done stained glass for maybe 10 years, just small things mostly for the enjoyment of making things for myself or as gifts. I recently purchased a used a Jen-Ken Kiln Bead Annealer with a 4 " flip door and with a AF3P ore-programmed "One Smart Controller". After several attempts I have ALMOST got the fused barrettes right, EXCEPT for they all have many "points" of sharp glass around the edges after fusing. I have tried gently grinding them off then doing a fire polish. It did work, but would like to know a way to NOT have the "points" on them to begin with. I asked on a Yahoo fusing group I belong to, and the below #'s were suggested to me. 500 to 1100; hold 30 500 to 1460; hold 20 <<<<< this segment would adjust up or down in time/temp depending upon results AFAP to 950; hold 30 I tired it, the glass looked like it barely got fused at all. SO could someone there suggest something different. I don't want to give up ;-)

there are some texture molds that are 9x9.....if i have a project 12 inches in length that needed texturing how could i accomplish this......do i need to buy (2) 9x9 to get the 12 inches......do i need to put a piece of thin fiber paper at the connection????

@greenthumbjen there is no limit to how many times you can fire a project. However, the more times a project is fired, the greater the risk of devitrification, especially with opal glass which tends to devitrify more quickly than transparent glass.

@comments2 thanks Jennifer. I used 2-3shelfs all the time but will try a little slower ramp up and see. I will try fusing them back together. How many times can glass be melted?

@greenthumbjen It sounds like you're firing in a ceramics kiln, which is fine. Glass requires a lot of heat circulations to ensure even heating so shelves stacked directly on top of each other are not recommended. Try slowing to 300 degrees per hour and add a 15 minute hold at about 1000 degrees to let the glass reach the kiln temperature before proceeding.

@Laceyboo I would not use granite. Have you ever put any rocks in a fire? they explode or at least crack most of the time and granite is afterall a rock

Please Help!!! I have been slumping bottles in my kiln for the past 2 years and last year started to fuse glass. I have been very successful being it is a large pottery kiln. I slumped a fused coe 90 piece a couple of weeks ago along with some specialty bottles a friend needed. everything great. I fused some very large pieces of glass art and they all came out great. I went to slump 3 large pieces of already fused glass artwork, one on 1"fiberboar with a whole cut out , one on a stainless vase cylinder and one on a Ceramic ring that I had used before. I ramped up the kiln at 500 degrees per hour and once it reached 1300 degrees I cooled to 980 and closed back up and soaked and then cooled. when I opened the kiln to cool the first time I thought the top piece already looked broken. all three levels were broken. Too hot on ramp up when glass is already fused? Bummed Jewelry has come out great and because I have all the pottery supplies I can make countless shapes to slump on and into. I really thought I ramped up at 500 degrees the last time but may have done it at 400 degrees I really did not think that would make a difference.

@cscheydt as long as you are using a decal that matures at a tack fuse temperature you can absolutely do both at the same time. Gold and other high-fire decals should be done in a separate process as they require hotter temperatures.

Hello, Question for the gurus. I want to fire a decal on and at the same time, perform a tack fuse. Can I do this. I have already performed the full fuse on two pieces of Spectrum 96 glass. Now it is time to put the decal on, I have allowed it to dry overnight. I want to tack fuse a pebble onto the same piece.

@Lynn D I'm unclear on what you mean by dragging but sharp edges can be caused by sticking so if that's the case wrapping your kiln board may help. There are several products that can be referred to as kiln board and each have a varying lifespan however most can be used more than once. For this project you can use a diamond hand file or grinder to get rid of the sharp edge.

I recently made some pocket vases using 3 layers of kiln board (1/8") and the edge of the top dragged and is pointed and sharp. Any suggestions? I thought of wrapping the kiln board with kiln paper... And how often can you re-use the kiln board? Maybe that's the problem. This particular set was fired once before. Thanks!

@Laceyboo it is absolutely okay to cut down a flat texture mold to fit inside your kiln. Exceptions, of course, where cutting it would make the mold crooked and might cause your glass to run off the edge.

Is it okay to cut down a textured mold to fit a smaller kiln?

I recently purchased the Jen-Ken Pro Fusion Fiber 11. I am trying to cast small items (colour de verre holey heart) on a small piece full fuse program; and also larger items (1/4 inch thick x 6 inches wide) on a large piece full fuse program - both with the kiln floor kiln washed and a thin kiln paper sheet fully underneath. The small casting did not fuse smoothly on the bottom (used kiln washed mold) and the large piece simply did not fuse together. Do I need to by a kiln shelf to cast in this kiln? Any suggestions appreciated as I am really bummed to not be able to use this for simple casting.

@Laceyboo Utilizing pieces of granite for damming purposes within a kiln for glass fusing/casting is not something we have attempted, therefore not something we would recommend using. Instead items like Delphi item

I'm wondering if anyone can tell me if I can use granite tiles as a glass dam for fusing. I have granite "samples" that vary in size from about 3" x 4" and 3" x 6". One side is polished. I was thinking that if I lined them with fiber paper and thin fire paper that I could use them as a dam. I don't want to ruin my kiln. I previously used them in my fireplace as a brace for the screen. I'm pretty sure they are dried out. Any ideas or help will be greatly appreciated. Thanks!

@mary p. It is not recommended to use casting molds within the microwave kilns.

Can the small casting molds be used in a microwave kiln?

@DelphiAnswers Thanks so much!

@kellbwm Yes, you can fuse anything to itself. You take a risk when fusing untested glass because it s just not formally rated for exposure to such high heats watch out for devitrification and be aware that glass containing more than two colors can be especially temperamental. Proceed with caution.

I have quite a bit of stained glass that is not rated coe. Am I able to fuse it with pieces from the same sheet? For example, I have the #8055 Sky's the Limit Glass Pack. Can I cut two 2" square pieces from the same sheet, stack them, and fuse them together? I would like to also apply one of the black enamel decals. Thanks for your help.

@Charlotte D., for mold repair use bisque fix- item 85017 :)

Does anyone know what kind of glue to use on a ceramic mold for fused glass?

When making cabs I use a 6x6 inch base glass and add my dichroic and top glass, I do a tack fuse with the dichroic and then a full fuse and then a full fuse with the clear topper and sometimes I still get craters. When this happens I clean the crater as much as possible and add the ends of my cab sheets that are too small to use or large pieces of scrap glass, I do a tack fuse add more glass as needed and then a full fuse, if possible I also do the full fuse with the top (clear) side down, any air that is left seems to rise to the back and not the front. Vitek, I had the same problem I watched a beautiful and thick plate crack and fall apart. I put all the pieces into boiling water and then froze then, after thawing the pieces back out I put everything in the tumbler for a couple of hours and out into the garden. It looked pretty and really added some umph to a dark area.

@TheDelphian A couple of years ago when I was getting ready for a show my kiln got sick would only heat up to a tack fuse, it did make some really nice pendants that ended up being a big seller but also taught me something, when I am using frit in jewelry molds I use the biggest pieces possible and I take the glass to a take fuse first, add more frit and take to a second take fuse and then to a full fuse. This really cuts down on any bubbles or hazing in the glass.

@Vitek Sorry to take so long getting back to you. I am very interested in this. Could you e-mail me at [email protected] ? I would like to look at your order so that I can investigate the glass you purchased. Thank you julie

Glass was all System 96 from Delphi. I have left the plate in the mold on the shelf and it has been cracking into more pieces every couple of days. Certainly was stressed in some way. Kinda interesting to check on. Never had this happen before.

When glass has cracked several days after firing it is generally caused by using glass that is not compatible. Review what glass you used and see if they were all of the same COE. Refiring will not fix the problem and trying to use it in another piece would be risky.

My 12" system 96 white background plate with black opaque and transparent blue overlaid design came thru the full fused phase just fine. I cold worked the edges a little and then slumped into a shallow bowl form. Again looked good. I have a Jen kiln and followed the pre-programed firing schedules. However several days later the piece cracked across in the middle. It went thru anealing at 960 for 1hr and then left in kiln until room temp. What caused this? How to avoid it? Can I "fix" it by putting the two halves together and refiring it? Or can I break it up and use the pieces in another piece?

@whatever68 Hi, just read your comment on moving glass, I "glue" my smaller pieces of glass with clear nail polish, the cheaper the better. I get mine from Walgreens and only pay 99c each. Hope that also helps.

Can you tell me a bit about the glass you are using and your firing schedule? How big are the pieces you are firing and what type of kiln you have. What is the thickness of the glass. ex. two layers of 3mm or thinner, thicker? Is the design two pieces of the same size stacked on top of each other or are there smaller pieces laid out in the design on top of a single sheet?

@charlaatd I use shelf liner and still get huge bubble that break open to a crater...help easyst

@kelihiett I too ned help with large crater bubbles easyst

@jwhitehead I don't know if you ever got an answer to this. You did get a bubble that popped. You can prevent this by firing on 1/8" thick shelf paper. This will allow the trapped air to vent out through the paper fibers instead of through your glass.

@preciouspeacock. Devitrification can occur when the glass has been heated too long as well as from high temperature. Therefore you might experiment with the length of time you are annealing. We find that two hours is sufficient and anything over that is not necessary. We generally will hold a 12"x12" - 1/4" thick piece for 60 minutes. As the size and thickness increases so does the anneal time with two hours being the top.

@jhaan Thanks for this .I have always thought glass had to be cooled very quickly through the devitrification zone to avoid greyness hence the flash cool.I must have misunderstood or read some conflicting information. I will check out the system96 website

The first thing I noticed is the use of flash cooling. This rapid drop in temperature will cause stress to the glass. The glass should be allowed to cool slowly reaching the annealing temperature. Some glass manufactures recommend stepping the cooling temp down again after the initial anneal as well. The System 96 website has a Firing Guide showing this process and can be used with both COE's. Larger pieces do require more control when firing so keep a good record of what works and what doesn't for future reference .

April 18, 2011 This is not a comment it is a question or rather a plea for help.I make fused glass pictures in the uk.Recently I have two 12" squares which have cracked across one corner one after more than a year of moving from gallery to gallery. Before fusing I soak at 555c for 1 hour then soak again at 671c for 30 mins then fuse at 780 around 10 mins then flash cool.Finally I soak at 516c for 3 hours or four and then turn off the kiln and cool usually overnight. My kiln is a top loader paragon pearl 18 clamshell firebrick. larger pieces are drilled at the edges and screwed to board. Do I need to slow down my cooling process?or is my approach all wrong for this type of work.I have had no trouble as yet with panels which are smaller 6 or 8 by 12" and layered 2 thick. I was a jeweller for 20 years and discovered dichroic and fused glass about five years ago.I made glass jewellery first which worked very well.Then clocks and finally panels adjusting my annealing each time. These works are usually no more than 8 mill thick in any place though there are different depths in them and sometimes bullseye and wasser together. Any ideas and help would be most appreciated Yours Deborah A very confused by all the annealing info I have read recently uk glass maker

There are a couple of things that could cause the problem you are describing. One, your kiln or kiln shelf may not be level which could cause the glass to shift if there is any movement around the kiln or within the glass. Second, you might try ramping at a slower rate. When working with several layers of glass, in your case 3-4, it is important that the heat is distributed evenly. If the outer layers become hot and the interior is still cold the difference in temperature could cause some instability. By ramping slower it will give each layer a chance to heat at the same rate. Try holding the temp at 1150F for 10-15 minutes as well to allow the heat to become saturated throughout. You could use the firing glue (not diluted white glue) which will burn off at the same time as the kiln paper. Usually around 900F. This may give you the additional hold you need. You can vent the kiln if you feel that the surface of your glass becomes cloudy from the organic material burning off.

Hi, I am new to glass fusing and I really hope someone can answer this question. I have been using Spectrum 96 tested glass with CBS96 Dichroic. After I get my pieces (all smaller than 2" square) set up on Bullseye Thinfire Paper on the kiln shelf and start the kiln I check thru the window and can see nothing has moved. but every time the kiln reaches about 200F, I notice the pieces have all come apart. Why is this happening. I have seen where some people use diluted glue to glue pieces together, but I am under the impression that the glue will only hold till about 300F, so eventually they will slip around again. Ramping @ about 350F/hr when occuring. Using 7x7" ceramic shelf on 1/2" kiln posts. Venting top about 1/2". Also, most pieces are 3 or 4 layers of 3mm glass sheets, all smooth and stacked solidly. Thank you for any help!!!

Regarding the hole in the middle of a fusing slab. I have learned that this is more common with 96 coe glass, used on top of kiln wash. It will happen to any glass but 96 is usually the cuprit. It is an air bubble that grew until it burst, this is usually caused by the glass sticking just a bit to the shelf, if I understood correctly. The problem is easily solved by using shelf paper instead of kiln wash.

I am new to glass fusing. The first project I attempted worked out great. Everything since then has had 1 to 3 huge holes in the project. What am I doing wrong?

Hello CM, Needling or spiking is usually caused from firing the glass to high, the glass spreads out and then tries to pull in to become the 1/4" needed and leaves those behind but still attached to the project.  We have also found that opaque glass also likes to do this.  The solution to fixing this is after it has happened is to use file such as item 60111 to get those off and if needed you might have to fire polish the project.

What causes 'needling' on fused projects? CM

I posted this in the System 96 section earlier instead of here in fusing--please excuse:) I just received my kiln this week and am new to fusing.  I did my first firing of some pendants and they seemed to have some sharp edges that will  need grinding  and lost all dimension.  They are still usable, but not the result I was looking for especially for the pieces with dichroic glass.    I did a full fuse.  Should I have done a tack fuse?  Also had quite a bit of kiln wash stick to the colored glass bases, but not the black or clear.  Is this normal?  I am using the System 96 glass and my Delphi Studio Pro Delux kiln.

The wash away kit doesn't work as well on pieces with heavy kiln wash stuck on them.  It does give the glass a frosted/etched look at times if it cannot get the wash off.  You could also try to soak the glass in vinegar and water for a long period and then try the brush on it again.  If that still doesn't work, try the 975 degreee back magic on it, at least it will shine it up and make it look like you meant to do that!

  Once you have bubbles trapped in your glass there are no real easy fixes. You can break the bubbles open and pour frit into them. You need to pile the frit a little higher then the glass. Sometimes you will still end up with little bubbles in your piece.    One way to avoid trapping bubbles in the glass (especially if you have glass pieces suspended between two or more layers) is to prop up the outer edges with glass frit. This allows the glass to sag in and all around the middle pieces. Then the glass seals its self from the center to the edge, allowing the air to escape. The cons to this method are that you often have to grind the outer edge, due to the excess glass frit you added to prop up the lip.

 Hi everybody --    I'm fusing some small dishes, and had some trouble with the kiln wash sticking to the back of 2 of them. So, I got a bottle of "Wash Away", and followed the directions, and it didn't work. So, I thought maybe soaking the dishes in the Wash Away for about 15 minutes might work. It didn't. Not only that, but now the dishes are etched!  Is there a fix to this? Can I refire/fire polish to get rid of the surface etching? Or are these projects toast?    Thanks! Tina

Hi, I have been fusing for about 2 yrs. so I know why these huge bublbes apeared in my glass. However, is there anything i can do to save the glass??  If I fused clear over the single piece of glass (along with the design), would that maybe make the huge bubbles I have in the piece go down!!  Thanks, nancy

Between 90 and 96 coe there is no “best”, just different. 90coe glass has been on the market longer and currently has more variety (textures/colors) available, especially in the dichroic glass selection; however 96coe tends to be a little less expensive. Other than that the big difference between the two coefficients is that 96 coe is a softer glass than 90 and therefore takes a little less heat, aprox 20-30 degrees less, to slump/tack/fuse. In the cabochon mold I would recommend using Primo Primer Kiln Wash (48235) which is specifically for casting style molds. Choose the coefficient you wish to use for this project and fill the kiln washed mold to slightly heaping in the center.               400 degrees/hr to 1000 degrees (F)             Hold for 10-20 mins             400/hr up to full temp 90                                                                 96 1480 degrees               1450 degrees             Hold for about 10 mins             Bring temp down to 970             Hold for 20-30 mins to Anneal             Turn off kiln, let cool.   Optional: Use 975 Back Magic (7323) to help shine up back/edges, follow product instructions. Done.

I'm usine the rainbow dichroic frit to make 1 inch cabachons in a mold. Which is the best frit to use 90 or 96 and at what temp should I program to use for each?

Delphi does sell those decals, they're the Fuseworks Fuse Art Decals-specifically the Floral pack (427867). If you wanted to create your own words/lettering you could also use the Creative Images Color Slide (8303) or the Fusing Photo Paper (8301). 

A Decal question. I saw a couple of pendants that had fused decals on them ut they also had lettering that looked like it was a decal of some type. Does delphi sell these lettering decals or where can I get them. The pendants said hope, inspire and dream. Sorry if I have posted in wrong place

You said in the other comment that you were using fine frit...the "pitting" is from the air bubbles that are trying to escape and popping on the surface. The finner the frit, the greater your possibility for bubbles/pitting. This is from air getting trapped between the small particles of glass. Using medium or course grit frit will help reduce the "pitting" effect. Temperature also plays a role in creating bubbles. Slowing your ramp rate down and not "over cooking" your glass will help reduce the pitting/bubbles. Ramp at 300 degrees per hour up to 1450, hold for 15-20 mins. When cooling, don't forget to hold at 970 to anneal.

Somehow my earlier comment ended up in a discussion about band saws, hope I get it right this time. What is the cause of surface pitting?  Some of my 1x1 tiles get it, other times not.  Seems like there are so many variables! Frit size, kiln temps?

What size frit are you using? The smaller the frit size the more "cloudy" or frosted it will look. Smaller frit captures more air between the pieces creating tiny little air bubbles which make the glass cloudy in appearance. Try using coarse frit or actual chunks of broken sheet glass…as long as it fits in the mold, and see if that solves your problem. Using a slower ramp rate when heating the glass will also help, this allows more time for the air to escape from in-between the pieces.

 I bought the round and square mini cab molds but everything always comes out sort of cloudy even tho I used clear frit. It's not devitrification; it's clear and shiny on top but the interior is kind of cloudy. What causes this?  

I am having the same problem except I have 3 holes. Can anyone help? Thanks.

I'm still very new to fusing and just had an experience that I hope someone can help me with so I don't repeat it again!  I was making a blank - full fuse using Bullseye 90 COE glass, according to the fusing schedule that came w/ my kiln.  My glass was a clear thin piece, 7x7, topped with a regular 3mm transparent piece of glass 7 1/8 x 7 1/8.  When I looked in my kiln just now, it fused perfectly - except for a nice 2" hole just off center! Did I get a bubble?  What might have caused it?  This was my first time firing a blank that size - I've only fied two other blanks that were 4" square.  Also, this was my first time reapplying kiln wash because it was cracking before.  I had to lightly sand to try and get it all off before reapplying again.

I would first make sure that the bottle is cleaned well with rubbing alcohol and make sure you are not holding very long at the high temperatures as that is what causes the hazing which is called devitrification.  It helps to apply Super Spray (item 7404) prior to fusing to prevent this or you could also apply it after to reverse the devitrification.

Thanks for the tips they really help! But I only have one problem. When I tried to slump a green bottle, I noticed that the bottom by the fold is a little hazy, not shiny. What did I do wrong? JM