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Posts posted by CactusPots

  1. The arrows pointing to 1 and 2 are separate pieces of metal or machined from one piece?  They should be one piece, but if you're questioning the seal across the machined surface of 2, I don't see how you're saying this problem was caused.  A failure of gasket or seal across the machined surface should cause a failure on the machined surface of 2, I would think.  I'm thinking an expert machinist or metallurgist opinion would point to a manufacturing flaw.  That's really a localized corrosion. 

    I'm thinking the fix is going to be either a replacement part or grinding out the corrosion and refilling and machine work.  Expensive either way, but Shimpo's "clean every time you use it" is not the industry standard for pugmills.  I don't use porcelain, so maybe someone else has a contrary opinion.    If you can bring expert opinion to Shimpo's attention, they may reconsider their position.  Them replacing the part would be the best case.

    resize Shimpo.jpg

  2. Ok, sure, but it's only degrading in one specific place.  Why is that spot different?

    If the lower cast part and the machined surface are 2 different pieces, is that seam where the sealant is needed?

    Has Shimpo seen this picture?

    If they are going lame on this, my suggestion would be to take it to a machine shop that does stainless and ask their opinion.

  3. Have you talked to Shimpo about this?  Is the upper part that is corroding so badly steel inside the clay chamber?  That seems like a bad design flaw to me if so.  I would think everything in the picture should be one part cast and machined aluminum.  

    I would be important for people considering purchases from Shimpo to hear how they respond to this.

  4. 17 hours ago, Rockhopper said:

    @CactusPots Would you put the shelf directly on the kiln floor ?  I've always had a shelf in the bottom of my kiln, but on 1/2-inch posts rather than directly on the floor.  (Don't remember the details of why - just that "someone" said I should do it that way.)

    In my electric kiln the shelf is on a layer of ceramic fiber.   The fiber extends all the way under the side walls, making a nice tight gasket.   My gas kiln the bottom shelves are on 1/2" posts.  The electric kiln is only fired to 06.  Seems to work fine.

    I was just pointing out that the work should not be directly on the soft brick, in case that isn't obvious to all.

  5. Lots of unknowns in the original post.

    I guess the base assumption is that the poster has an electric kiln unless stated otherwise.  We also have to guess there isn't a shelf on the bottom of the kiln to protect the soft brick.  Also no information about the type of clay used for the tile.  If terra cota, not so bad.  If porcelain,  


    I'm with the Rockhopper, this is a disassemble.  The glaze will eat into the soft brick like soap into a sponge.  The tile being much harder than the soft brick will make it difficult to remove without destroying the brick.  My advice would be try the grinder, but be ready to go to a diamond head on a dremel.  Once you get it basically flat, set a shelf on the bottom as the new base.

    Just how did you manage to get a tile flipped upside down on the bottom of the kiln?

  6. On 1/9/2015 at 2:04 PM, bciskepottery said:

    All I know is that mine will be around a lot longer than I will . . . so, if you adhere to the old saying about the importance of first impressions, make sure you reduce your seconds and discards to tiny shards and only your best work survives for future generations yet to come to find.

    I would say the assumption behind this statement is that future cultures will not appreciate or value imperfections.  Every creator sets his own standards, so I'm not criticizing this viewpoint, only pointing out it's limitation.  You don't have to be a science fiction fan (although it might help) to imagine a world where handmade is no longer possible and replicators churn out perfection after perfection.  I can assure you within the lifespan of our work, the values of societies will change.  What was once trash soon becomes treasure.

  7. There is such a thing as commercial black grog.  I got some from my supplier, but I don't know it's ultimate source.  It's similar in size to the regular grog. 

    I've settled on applying a mix of white sand blast sand, red sand and black grog to still wet white shino.  Fired to cone 10, it's a pretty good even surface of sand.  It doesn't melt.  If you use a shino with good percentage of soda ash, it comes back with an orange background.

    As for the homemade grinding, I'v tried that with glass to get an additive for my wood ash glaze drip mix.  A lot of work, unless you only need a little bit.

  8. It took me a long time to make 6 mugs at once that I really like all 6 of them.  I find mugs to be difficult because of the ergonomic issues.  It must feel right to the hand, the lip, right size,  right weight.  Proper glaze, balanced look.  Kitchen ware isn't my main thing, so I didn't work at it all that diligently, but I can tell you all my friends have bad mugs.  Denise's advise is how I went about it.  I have 3 mugs from the same full time pro potter that I use every day.  Perfect for me, but all 3 have rim chips and discoloration inside.  Plus I have mugs from a dozen or so other potters I don't care to emulate.  Make lots of mugs and be hyper critical about them.  Have lots of friends and family.

    I wouldn't make anything deliberately that I didn't like hoping someone else would.

  9. 16 hours ago, Mark C. said:

    (screws were rusted.) my guess is it was aSkutt kiln with non stainless screws from the old days.

    I buy real quality stainless screws and use them in electrics-any hardware has better screws than those supplied .

    I don't think anything on the Skutt is stainless.  Looks like it but it's not.  Keep the outside clear of glaze splashes, they will rust there.

  10. 1 hour ago, neilestrick said:

    Inspect the lid band. It may just be particle buildup on the surface from the fumes coming out the peep hole. If it's eating through the metal replace the band.

    It seems to me that the fumes from bisque firing must be highly corrosive.  Don't know what happens in electric glaze since I don't do that.   I did lose a lid myself by not being aware of the amount of corrosion in the band.

    Now is the time to deal with issues like this.  It's so easy to concentrate on the fun part of studio ceramics and lose track of maintenance issues.  Go through the kiln and clean up all issues before you start using it is my advice.  No mickey mouse fixes.  Replace with new.

  11. It's just the hot water to clean a wax coated brush.  I've been known to leave a wax brush overnight.   Boiling water is 100% effective on wax.

    An electric tea kettle is a necessity in my studio.  Hot water for throwing, mixing soda ash and cleaning wax brushes.  Occasional cup of tea.

    The soap trick on the brush works ok for latex resist.  Maybe 85%.  Use cheap brush if possible.  When I get chunks of latex that won't come out on a good brush,  I use a wire brush to clean it.

  12. 3 hours ago, Bill Kielb said:

    The interesting point Is there is probably no better time to fine tune the  primary air. It’s super easy to watch your O2 meter, go into heavy reduction and establish the best opening for the burner. They are hypersensitive at this point So this is easy to do. Any other time, no matter how much you turn things they pretty much seem fine which is why most folks just set them somewhere as best they can.  With the O2 probe available, now another tool that allows these to be tuned easily.

    That was what I was hoping for, but I couldn't find an adjustment of the primaries that made a difference on the meter at the point of heavy reduction.  Now it will be fall before I have another glaze fire, but I'll fool around with it some more when I get there.

  13. A friend of mine who does handbuilt planters and single fires uses a lot of iron wash.  He uses steel wool for the wipe back.  I don't really like iron wash by itself.  When it's thick it gives a shiny metal look that isn't right for my taste.  Lately I've been using this rutile wash that's a nicer mat brown where it's thick in the crevices

    Ball clay 25   Neph Sy  25   RIO  30  Rutile  30   GB  30. 

  14. At 80 on the oxyprobe I have a distinct gas odor.  Not black smoke, but the exhaust is visible.  I always adjusted the primaries to less than a quarter inch at reduction because I thought, but had no way of knowing that cutting the primary air would increase reduction.  Mine are at least accessible, the kiln is open on both sides.  The West Coast kilns that I learned on were not accessible.  That was a long time ago.

    I really have this kiln down to the basics for firing.  I don't know where to go for any improvements, but my personality won't leave it alone. :) 

  15. When I use iron (mostly) oxide for textures, I wipe back the high places with a wet sponge to get maximum contrast.  Once the wash is dry, I've never noticed iron coming off in the glaze.  I usually add some dark clay and magma to the wash and I think that helps give it a more durable surface.  I didn't always do that and didn't notice the problem then.

    As for spraying, it's more wasteful of glaze than dipping, but if you like that approach, the best bet is a compressor and air gun.

  16. Some of the information I was able to gather yesterday's firing.

    At 1600, which is where I would normally start reduction, the kiln is already registering about a 34 on the oxyprobe,

    My gas and damper settings for reduction run it to 80

    The kiln will climb to finish, very slowly at the end, but very even temperature top to bottom.  It will register a lower oxyprobe number as it goes by itself and I usually make a few small (1/8") adjustments to the damper to move things along.  Pretty consistent 12 hour firing.  Soft 10  Oxyprobe number at finish was 485  36 cubic foot kiln used 25 gallons propane

    Correct me if I'm in error, but my take away is that the primaries are largely irrelevant for reduction firing. 

    I prefer to bisque in the electric kiln, but if I was to use the gas kiln, that would be another set of questions. 

  17. ___________________________________________________________               __________________________________

    __________________________________________________________               ________________________________     Brick floor of kiln

                                                                                                                    What is the space between the bottom of the brick floor of the kiln and the top of the burner?  

                                                                                                                        ---------   top of burner

                                                                                                                       |                |    

    and why does this double space with the return key?

  18. 11 hours ago, Bill Kielb said:

    Here is one we just finished fine tuning. Geil I think, propane. Works like a charm. Pictures of close up of burners and penetration as well as imbed depth. Notice air shutters adjusted positions. This was pre-tune. After fine tune in reduction these ended up about  1/2 - 3/4 closed to get the oxidation fine tuned or to its maximum oxidation. Wide open did not produce the best  amount of primary air. Added pic of upper sight port at early reduction / tuneup time to give you a sense of how pressurized this kiln is during adjustment.




    Bill,   On this third picture,  I see the burner penetrating the floor of what?  This is not the floor of the kiln, I don't think.

  19. A-  Turn up the gas  From about 4" at 1600 to 6" the rest of the way

    B- the damper in by about half.

    Slight adjustments to the damper (1/8" per) to get temperature rise to finish.

    I had a suspicion the primaries adjustment wasn't making a contribution to reduction.  Now I want to know why. 

  20. 49 minutes ago, Bill Kielb said:

    Definitely telling you something if you can adjust your primary air fully closed and get no change dont you think?

    Not cinched down, just to a few mm.  What would you say it's telling me?  I would guess the burners are able to draw all the air they want from the gap between the burners and the floor.

    I'll have to get back into my kiln building reference books and see what the gap is supposed to be. 

  21. It doesn't appear any adjustment to the primaries makes an impact on the reading of the oxyprobe.  At my normal setting, I reach reduction temperature at 1600 with an oxy reading of 31.  My usual setting for reduction at that point reads 81  The kiln climbs about 100 degrees or so for the hour of heavy reduction with the bottom eventually passing the top (down draft).  Maybe it just doesn't matter.

    I should watch and see if Geil ever does another firing workshop.  My kiln is more like his that any other.  Since it's a homemade job, maybe there are peculiarities.  

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