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shawnhar

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  1. Like
    shawnhar reacted to Denice in Melting glass bottles   
    I did glass casting with recycled glass,  I was melting it into bisque molds.   I had to do a lot of testing to find the right schedule and firing temperature and annealing process.   One thing I did find is that most bottle glass is tempered  and will slump but takes a high temp to melt.   I use crushed window glass  for a blue green glass and cheap clear glasses from the Goodwill store for my clear.    The thicker the castings the harder it is to fire and anneal correctly,  my castings are a inch thick and it took 21 hours and that was as fast as I  could go.      Denice
  2. Like
    shawnhar reacted to Min in Melting glass bottles   
    One thing I found out the hard way was to either use really flat shelves or put a little mound of alumina hydrate under the far edge of the bottle if your shelves are at all warped. Bottles can roll, I had a couple roll and fuse together. The alumina hydrate acts as a speed bump to stop the bottle rolling and just brushes off after the firing.
    Genesis controller comes with this schedule for slumped bottles.
    500/500/15 hold
    500/1000/15 hold
    600/1250/20 hold
    500/1475/15 hold
    9999/1100/30 hold
    200/970/30 hold
    120/750/10 hold
    off
  3. Like
    shawnhar reacted to Roberta12 in Melting glass bottles   
    Neil is correct, there is a lot of info out there.   The firing schedules will depend upon the size of your kiln.  You need to get your ramps up to a certain temp and then hold, and same with cooling.  A controlled cooling  with help with devitrification, a cloudiness on the glass (like crystallization)  I slumped a lot of bottles when I got my kiln, once I figured out the firing schedule, for a 7cu ft kiln, the bottles paid for a lot of clay supplies.  The material was free (people dropped off their empties at my house) and it was a trend at the time.  Shorter firing time, less electricity, all that.  Now I slump about one load a year, someone wants a bottle for something special.  I really do like finding another purpose for glass bottles!   I have a customer who buys the slumped bottles from me and incorporates them into her stained glass work.
    Roberta
  4. Like
    shawnhar reacted to neilestrick in Melting glass bottles   
    It's pretty simple. Do a Google search and you'll find lots of firing schedules. You want the bottom of the bottle to be nice and smooth, so start with a fresh application of kiln wash, as smooth as you can get it. The glass will pick up every little bump. Ideally, use an unwashed shelf and kiln paper.
  5. Like
    shawnhar reacted to curt in How long is too long for Greenware   
    However, understand that “dry” doesn’t necessarily mean leaving a pot just sitting out on a shelf somewhere.  If you live in a climate that cycles through wet and dry seasons, and  cold and hot temperatures extremes, humidity levels in the air can also move up and down substantially over time.   This affects things made out of clay which have not yet been fired.  Dry pots absorb and desorb lots of water from humidity in the air, through the small channels in and around clay particles.  Unfired clay effectively inhales and exhales humidity over time.  Think of it a bit like a rigid sponge.
    This matters because clay shrinks and swells as it’s water content changes.  While most of the shrinking happens in the day or two after we take a pot off the wheel, shrinking and swelling stresses are still at work in a small but meaningful way even when we think of the pot as “dry”.  
    And different temperatures also promote water movement, in the pot as a whole, and also in different parts of the same pot.
    Humidity fluctuations may or may not matter, depending on your clay body and what is in it.  Big, gutsy clay bodies which are relatively “open” ie a good range of large and small particles sizes with grog, silica sand or other aggregate strengtheners, along with sufficient colloidal material may have very good “dry” strength.  Fine porcelain bodies have larger smaller particles, greater surface area, and smaller pore channels, but little in the way of aggregates to strengthen the body, and can be more fragile.   
    Different clay body ingredients can also impact how well a clay body withstands humidity cycling.  Sodium Bentonite, for instance, which shrinks and swells dramatically, is a common clay body plasticiser, and small colloidal particles like this are actually the main source of green strength in dry pots.   It is mostly not a a problem since our clay bodies have so little of it, but should not be forgotten, as some bodies lean on bentonite more heavily.   Ball clay shrinks and swells less than bentonite, but there is usually a lot more of it than bentonite in clay bodies we use.
    Point of all of this is that pots can be negatively impacted by humidity cycling, and to a lesser extent temperature cycling, causing weakness, cracks which show up later during glaze firing, and in extreme circumstances even dry pots disintegrating where they sit.   The longer you leave them exposed, the greater the risk.  
    The extreme version of all this would be if your studio is in a rainforest, and you leave a pot on top of the kiln you fire every couple of weeks, and which is also exposed to the sun on one side.   That should be the perfect storm. 
    Moral of the story is if you want your dry pots to last and fire OK later,  try to avoid putting them through conditions like this.
  6. Like
    shawnhar reacted to Callie Beller Diesel in Computer doesn't boot   
    My apple didn’t need a 16” sock. I got away with a (clean!) lady’s size 8. 

  7. Like
    shawnhar reacted to Smokey2 in Airbushing resist   
    I understand you are trying to be helpful, thank you.

    If I was going to order something online I would buy the spray shellac that I know works with my method. Instead I was looking for alternatives with something that I already have on hand.

    Even with the relief package from the US government there will be many small business that will fail during this pandemic. I'm talking about those business with 10, 20 or less employees.  Once this pandemic is over there will be an economic crisis and those small business that made it through  will be faltering and will need all the help to survive from their communities.

    Once we clear this pandemic I have every intention to support small local business as much as possible, even if I have to pay more. Jeff Bezo doesn't need my support
  8. Like
    shawnhar reacted to Min in In the Studio Project Image tutorials   
    Simple hand building project if anyone is looking for something different to try for a change of pace. My soft slab (olive) boat, it's an easy project, would be good for kids to make too. Turn it into a viking ship or ? I don't have any glazed right now but a couple bisqued ones in the last image.
    Supplies needed:
    Soft clay
    Rolling pin 
    1 1/4 - 2 1/2” diameter dowel wrapped in newspaper (or long thin rolling pin, diameter isn’t critical)
    Pony roller or piece of plastic
    Cornstarch (optional)
    Supports if you use soft clay
    1 - Template is 19” overall length, 4 1/4” wide. Each side measures 15 1/2”. Soft slab, cut out the pattern. Don’t worry about getting the ends exactly as I have them, you can just use one gentle curve from the point to the opposite side. If you want texture on the outside of the boat do it now.
    2 - On the long edges use a pony roller and soften the edge. If you don’t have a pony roller just use a piece of thin plastic, hold it taunt and run your finger along the edge. (2a)
    2a- Flip the piece over, if you want texture on the inside do it now. Soften the long edges on this side too.
    3 - Cover up the ends and lightly dust the clay with cornstarch. Since my clay is very wet I don’t like to use a pounce, I just load a brush with cornstarch and tap the brush over, but not touching, the clay.
    4 - Lift the slab and lay it cornstarch side down over the dowel wrapped in newsprint. 
    5 - Press the clay around the dowel then flatten the bottom with a small rolling pin or pony roller. The dowel I use is a bit narrow so I lift one end up while doing this so I don’t crush the long edges of the slab.
    6 - Moisten the ends with just a few drops of water if you are using soft clay. If you use firmer clay then use a tiny bit of slip. Bring the long edges together at the ends of the slab and pinch the lower edges together. I keep a slight overlap so I can fold the overlap over and work it in with a rib so the boat doesn’t leak. 
    7 - Roll the top pointed ends into spirals, covering the join.  One ends rolls to the left, the other to the right. Transfer the boat to a drying board.
    8 - Straighten out the rim, flute the edges if you like. I use bendable hair rollers to support the sides while drying. Clay coils would work too. I’ve found with my clay I need to dry these slowly or they lift up in the centre. You could also put a small weight in the centre to help prevent it lifting. 
    Would love to see some other projects here!
    (Sorry but I can't get the numbers to show up on the images, read left to right 1-8)


     
  9. Like
    shawnhar got a reaction from GEP in Glazing big bowls/large objects   
    Thank you to to everyone for all the great responses! I know it has been a hot minute since I originally posted this but I finally got to try out the "brushing" on dipping glazes. I had some bisque pieces that were pretty much seconds to try it on and was super happy about that since  I am loath to lose more of my big bowls. I'm really stoked about this process and will make some test pieces to practice with, it's a bit of a learning curve as the glaze thickness and the brush seem to have a big impact, but the biggest thing is having a squeeze bottle with a small nozzle so you can control the flow, I had a restaurant style ketchup cheapo thing and it was terrible, just dripped out as soon as you turned it over, with no flow control, what a mess! I think with a decent brush and better flow control I will be able to get some great results on my big bowls.
     

  10. Like
    shawnhar got a reaction from Hulk in Glazing big bowls/large objects   
    Thank you to to everyone for all the great responses! I know it has been a hot minute since I originally posted this but I finally got to try out the "brushing" on dipping glazes. I had some bisque pieces that were pretty much seconds to try it on and was super happy about that since  I am loath to lose more of my big bowls. I'm really stoked about this process and will make some test pieces to practice with, it's a bit of a learning curve as the glaze thickness and the brush seem to have a big impact, but the biggest thing is having a squeeze bottle with a small nozzle so you can control the flow, I had a restaurant style ketchup cheapo thing and it was terrible, just dripped out as soon as you turned it over, with no flow control, what a mess! I think with a decent brush and better flow control I will be able to get some great results on my big bowls.
     

  11. Like
    shawnhar reacted to Min in Glazing big bowls/large objects   
    Thanks for posting your results Shawn, glad it worked so well for you!
    For the thin glazes you could flocculate  them up with some vinegar or epsom salts solution so they don't flow so quickly if you want the volume of glaze coming from a larger nozzle.
  12. Like
    shawnhar got a reaction from Rae Reich in Glazing big bowls/large objects   
    Thank you to to everyone for all the great responses! I know it has been a hot minute since I originally posted this but I finally got to try out the "brushing" on dipping glazes. I had some bisque pieces that were pretty much seconds to try it on and was super happy about that since  I am loath to lose more of my big bowls. I'm really stoked about this process and will make some test pieces to practice with, it's a bit of a learning curve as the glaze thickness and the brush seem to have a big impact, but the biggest thing is having a squeeze bottle with a small nozzle so you can control the flow, I had a restaurant style ketchup cheapo thing and it was terrible, just dripped out as soon as you turned it over, with no flow control, what a mess! I think with a decent brush and better flow control I will be able to get some great results on my big bowls.
     

  13. Like
    shawnhar got a reaction from Callie Beller Diesel in Glazing big bowls/large objects   
    Thank you to to everyone for all the great responses! I know it has been a hot minute since I originally posted this but I finally got to try out the "brushing" on dipping glazes. I had some bisque pieces that were pretty much seconds to try it on and was super happy about that since  I am loath to lose more of my big bowls. I'm really stoked about this process and will make some test pieces to practice with, it's a bit of a learning curve as the glaze thickness and the brush seem to have a big impact, but the biggest thing is having a squeeze bottle with a small nozzle so you can control the flow, I had a restaurant style ketchup cheapo thing and it was terrible, just dripped out as soon as you turned it over, with no flow control, what a mess! I think with a decent brush and better flow control I will be able to get some great results on my big bowls.
     

  14. Like
    shawnhar got a reaction from Min in Glazing big bowls/large objects   
    Thank you to to everyone for all the great responses! I know it has been a hot minute since I originally posted this but I finally got to try out the "brushing" on dipping glazes. I had some bisque pieces that were pretty much seconds to try it on and was super happy about that since  I am loath to lose more of my big bowls. I'm really stoked about this process and will make some test pieces to practice with, it's a bit of a learning curve as the glaze thickness and the brush seem to have a big impact, but the biggest thing is having a squeeze bottle with a small nozzle so you can control the flow, I had a restaurant style ketchup cheapo thing and it was terrible, just dripped out as soon as you turned it over, with no flow control, what a mess! I think with a decent brush and better flow control I will be able to get some great results on my big bowls.
     

  15. Like
    shawnhar reacted to CactusPots in Glazing big bowls/large objects   
    To do the outside of large bowl shape forms I use my wheel.  A large basin like a concrete mixing tub with sticks supporting the bowl.  Slowly rotate while pouring.  It can be done perfectly, but just to add that extra, I'll take the air compressor to it and blow the glaze evenly, eliminating any drip.  Messy, yup.
  16. Like
    shawnhar reacted to Mark C. in Glazing big bowls/large objects   
    When pouring glaze you should not have drips-The inside pour is a spin the bowl as glacovers insdie evenly than a drip on lip. Do the inside 1st always in large forms. The outside is also a spin with your hand inside (handling pots while glazing is a skill like throwing) there should be a even spin with one hand the other is pouring with whatever container you choose but overlaps should be avoided and the only drip is off the lip which you spin until its gone.
    I'll make a few YOUTUBEs after I die when I have time 
  17. Like
    shawnhar reacted to Hulk in Glazing big bowls/large objects   
    An ear syringe can be handy for spaces that have an edge, see ~5 minute mark in Hsin-Chuen Lin's vid: https://www.youtube.com/watch?v=T_BIm8lKGus
    Bisque grabbing can be mitigated - try dipping your brush in water, then glaze/underglaze; the material "floats" on the water and spreads, particularly if the objective is to fill chatter marks, carving, etc.
    For sharp boundaries, I'll tape, dip, wax, wait, pull the tape, then second dip. A burnished groove/line helps hold a straight tape line. 
     
  18. Like
    shawnhar reacted to CactusPots in Glazing big bowls/large objects   
    I don't know what is considered a brushable glaze.  I brush any glaze I have if it seems like an appropriate method for the form.  The Magma product helps with some glazes, I think, but the real trick, as always, is the right tool for the job.  Here's mine.

  19. Like
    shawnhar reacted to Mark C. in Glazing big bowls/large objects   
    Before I go any further with suggestions I need to know are these pouring -or brushing glazes???? I assume you where firing to cone 6 and were using dipping /pouring glazes-if all thats a yes then take my suggestions-if on the other hand they are brushing glazes please do not listen to me as I have not brushed a low fire glaZe in 40 years.I know how but that all-three coats going different directiuons if I recall right.
    Now in terms of too much (to thick)or not enough (to thin) this all takes practice and time to learn just as learning to throw did -its no different its a skill set.
    I love glazing and thats my fun part but I mastered it long ago-it sounds like you are like many who dread it. You need to learn to pour quickly and do not let glaze sit in the bowl. thinner is better than thicker on the inside. I spin the bowl while pouring out very quickly-you could practice on a stainless bowl and you will not waste glaze that way. Go pour a stainless large bowl 20 times and I bet somewhere along that line you will GET IT. Of course stainless will not absorb galze so that also another learning curve.
    I feel glazing is the next part of being a solid potter-another skill set -kiln building is another-firing (gas -raku reduction) another-they all take time and many stop at the throwing part and struggle with the glazing. Push thru it and master it.It took me a few decades to do it while asleep-maybe you can do it sooner.
     
  20. Like
    shawnhar reacted to Min in Glazing big bowls/large objects   
    It might be blasphemous but whatever it takes to get the job done!
    It's great that there have been a lot of replies to your question, there have been a lot of good tips here. I think the type of glaze is a consideration too, drips are fine if it's part of the look you're going for (or don't want to fettle them down). Fluid glazes that blend well together probably have more leeway than a stiff majolica type glaze as to application method.
    One other thought about dipping, overlapped glazes can be part of the design but if it's something you want to avoid you can use wax resist on part of the glaze. It's a bit of hurry up and wait because you have to dip the pot part way or even just where you want to hold onto it for the second dip / wax / wipe of the glaze below the wax / let the pot dry / dip the other side. Same as if you use wax over a liner glaze on a mug to avoid the liner and outside glazes overlapping.  
  21. Like
    shawnhar reacted to Mark C. in Glazing big bowls/large objects   
    I make huge bowls and always have 1 or 2 for sale.
    I pour 99.9% of glazes with dipping and brushing of under glazes (other cone 10 glazes) I pour the insides of most bowls and pour the outsides with a long nosed pitcher I have posted about many times-they come in two sizes and pour extremely well with great control. I use at least 3-5 of them on glaze day.
    https://smile.amazon.com/gp/product/B000PSB5VU/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
    As far as dipping lips I use a large plastic tub just like the ones that GEP shows in her photos-you can get these at many specialty markets-Koren ,Japanese or Mexican. I have a few huge ones that are larger than hers in Photo as well-its nice to have multi sizes to choose from.
    When I see one I always buy it as they are a bit hare to find. I drill a hole in the lip and hang it on the wall.
    I also have several 20 gallon buckets I use for some glaze that I use all the time so I can dip into those like my rutile blue glaze, its about 2 feet across .You can find those at restaurant supply stores.
    It takes some time to gather all that you need as a potter 
    Spraying glazes takes to long to do 35 cubic feet loads-brushing glazes is WAYYYYYY to much time for a production potter to do.
     
  22. Like
    shawnhar reacted to Min in Glazing big bowls/large objects   
    Forum member @Chris Throws Pots has a video on his website where he shows how to glaze on the wheel with a brush and a squeeze bottle of glaze. I can see this being helpful if you don't want to mix up a large amount of glaze for dipping.  I think I would do the outside first and hold the pot down with clay wads (if you don't have a Giffin Grip) and glaze up to those then do the inside and glaze over the rim and down to the glaze line on the outside.
     
  23. Like
    shawnhar got a reaction from moh in Anyone spray glaze their mugs?   
    You can "cheat" by dipping in a light color base glaze 1st, then spraying the darker glaze on, this way it doesn't ruin the piece if the sprayed glaze gets thin in spots, like behind the handle.
  24. Like
    shawnhar got a reaction from oldlady in 1st teaching gig, couples wheel throwing   
    Thanks all! I will focus on making it fun for them and maybe bring a bit 'o wine, lol.
  25. Like
    shawnhar got a reaction from Rae Reich in Anyone spray glaze their mugs?   
    You can "cheat" by dipping in a light color base glaze 1st, then spraying the darker glaze on, this way it doesn't ruin the piece if the sprayed glaze gets thin in spots, like behind the handle.
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