tomhumf Posted March 31, 2020 Report Share Posted March 31, 2020 I'm struggling with lids. I've just thrown a 8" wide casserole and lid. I measured the gallery and lid and made them exactly the right size to fit when thrown. I've let them dry a few days, now ready to trim and now the lid is about 1/4 " too big. Is this just because they dried differently and they should fit again when bone dry? Or do you generally have to make the lid a smaller size to fit? I've had trouble with this issue with butter dishes I've made before. Link to comment Share on other sites More sharing options...
neilestrick Posted March 31, 2020 Report Share Posted March 31, 2020 Which type of lid? Is the lid seating in the lip of the pot, or does the lid have a flange that fits inside the rim of the pot? Did you measure with a ruler or calipers? Link to comment Share on other sites More sharing options...
tomhumf Posted March 31, 2020 Author Report Share Posted March 31, 2020 The lid has a flange, the lid will sit inside the flange of pot on the gallery. I measured with a ruler. Like this https://images.app.goo.gl/ogY2hD1JV34mo5WYA Link to comment Share on other sites More sharing options...
liambesaw Posted March 31, 2020 Report Share Posted March 31, 2020 A double gallery, a little tricky! I have been making casseroles with just a lid gallery, and they've been turning out well. I have had to trim them into place a little but not any more than I do with any pot. The issue I have, if anything, is that the domed lid shrinks MORE because it shrinks in a dome shape, whereas the casserole only shrinks in one direction. Link to comment Share on other sites More sharing options...
neilestrick Posted March 31, 2020 Report Share Posted March 31, 2020 The flange and gallery together are overkill. You only need one method to keep the lid in place, so pick one. Also, measure with calipers, directly from the pot to the lid. A rule is not very precise. The calipers can get right into the space you're actually measuring, whereas a ruler can only get so close. If you do a seating in the rim of the pot, you can throw the lid oversized and trim it to fit perfectly. Link to comment Share on other sites More sharing options...
Hulk Posted April 1, 2020 Report Share Posted April 1, 2020 Tips picked up from Bill Van Gilder (one of his vids), always make extra lids, and in standard sizes - hence, a) when, err, "if" you wreck one in making process, there are backups, and b) your stock of bisque lids comes in handy when/if a finished lid goes (oops!) ping, or a Customer requests a replacement. I don't mind using a ruler - with care, +/- a quarter millimeter is simple enough, however, for smaller openings, a cheap plastic caliper is handy (I use the plastic caliper a lot!). Shrinkage difference can still bite between trimming and completion, leave a bit o' wiggle. That said, some fired clay can be polished away (wet diamond wheel). The shapes and thicknesses matter, I believe - trial, and try again! Link to comment Share on other sites More sharing options...
Babs Posted April 1, 2020 Report Share Posted April 1, 2020 4 hours ago, tomhumf said: The lid has a flange, the lid will sit inside the flange of pot on the gallery. I measured with a ruler. Like this https://images.app.goo.gl/ogY2hD1JV34mo5WYA I only use this type of lids on teapots. At trim stage you can always get a fit with care. I then dry both pieces together , lid upside down in pot. Link to comment Share on other sites More sharing options...
tomhumf Posted April 1, 2020 Author Report Share Posted April 1, 2020 Ok thanks all, I'll get some of those plastic calipers I think. I do have some wooden ones but I don't like using them, it just seems really tricky to measure because the ends aren't fine points. So is everyone saying I should try throw the lid and pot to fit exactly? Link to comment Share on other sites More sharing options...
Bill Kielb Posted April 1, 2020 Report Share Posted April 1, 2020 4 hours ago, tomhumf said: Ok thanks all, I'll get some of those plastic calipers I think. I do have some wooden ones but I don't like using them, it just seems really tricky to measure because the ends aren't fine points. So is everyone saying I should try throw the lid and pot to fit exactly? Yes, but leave yourself some room. Meaning if it’s a lid that fits inside it would be best so it has some room to fit. Trimming this space at the leather hard phase is another thought to keep in mind. Pots often distort a tad in the firing so perfect fits with no tolerance are really hard to achieve. My freshly thrown stuff will often include a 1/32” tolerance all around which ends up a really tight fit. Finally for casseroles an interior fit lid is important as you don’t want steam and condensation leaking out while cooking. So pick an interior lid style with a liberal tolerance that is forgiving to throw. Notice the very large gaps or tolerance in the drawing you posted? Link to comment Share on other sites More sharing options...
tomhumf Posted April 1, 2020 Author Report Share Posted April 1, 2020 58 minutes ago, Bill Kielb said: Yes, but leave yourself some room. Meaning if it’s a lid that fits inside it would be best so it has some room to fit. Trimming this space at the leather hard phase is another thought to keep in mind. Pots often distort a tad in the firing so perfect fits with no tolerance are really hard to achieve. My freshly thrown stuff will often include a 1/32” tolerance all around which ends up a really tight fit. Finally for casseroles an interior fit lid is important as you don’t want steam and condensation leaking out while cooking. So pick an interior lid style with a liberal tolerance that is forgiving to throw. Notice the very large gaps or tolerance in the drawing you posted? Right! Makes sense, ok I'll Chuck the first one away and start again with this in mind I think. Thanks everyone ! Link to comment Share on other sites More sharing options...
Pres Posted April 1, 2020 Report Share Posted April 1, 2020 Whenever I throw casseroles, I like to use the same clay for the lid as I do for the bowl. In other words, I wedge up a ball of clay, cut off 1/3 of it for the lid, and throw the base, then throw the lid using the same clay. In the long run it means that my pieces have a tendency to shrink at the same rate. I do not throw multiple bases then throw the lids. I also do as others leaving a small amount of leeway if I need to trim, but rarely have to. I have come to the point lately that I design the pots with a wider flange on the bowl to take care of slop-people are not always good with spoons, and it makes it easier to remove from the oven without a handle when using mitts. best, Pres bestm Link to comment Share on other sites More sharing options...
ronfire Posted April 1, 2020 Report Share Posted April 1, 2020 I like to glaze the tops of the pots as well but then have to fire the lids separate. The problems with this is some times the lid or pot distort and don't fit together. I have also made the fit to close and after the glaze they no longer fit. I make a butter dish that has to be fired separately in the glaze fire so I try to place the base and lid on the same shelf and not have the bell lid next to the elements to help stop distortion at cone 6. Link to comment Share on other sites More sharing options...
Min Posted April 1, 2020 Report Share Posted April 1, 2020 The speed and amount of time spent throwing the lid and base seems to make a difference in how much it shrinks too. I've found if I throw a shallow wide lid quickly it will shrink more than if I slow down how long I take to make it. I know it doesn't seem logical but I've seen it time and again when I throw lids too quickly. Link to comment Share on other sites More sharing options...
Pres Posted April 1, 2020 Report Share Posted April 1, 2020 25 minutes ago, Min said: The speed and amount of time spent throwing the lid and base seems to make a difference in how much it shrinks too. I've found if I throw a shallow wide lid quickly it will shrink more than if I slow down how long I take to make it. I know it doesn't seem logical but I've seen it time and again when I throw lids too quickly. Very logical to me. When you consider the time to make certain the dish/bottom, where the compression across the base is important to prevent the dreaded S crack, the time for the lid needs to be equivalent. I believe there were some selections in Hamer that touched on these problems. best, Pres Link to comment Share on other sites More sharing options...
Min Posted April 1, 2020 Report Share Posted April 1, 2020 On 4/1/2020 at 9:22 AM, Pres said: Very logical to me. When you consider the time to make certain the dish/bottom, where the compression across the base is important to prevent the dreaded S crack, the time for the lid needs to be equivalent. I believe there were some selections in Hamer that touched on these problems. I think it's probably to do with the clay memory. Compress bases and lids equally but it's the pulling out that I tend to have a bad habit of doing too quickly. My lids tend to be more shallow domed plate forms rather than like Liams one in his image above, not much clay under the center area where the knob goes. Link to comment Share on other sites More sharing options...
Pres Posted April 1, 2020 Report Share Posted April 1, 2020 Min, mine are much the same, sometimes with a higher dome, but most with a shallow rise. best, Pres Link to comment Share on other sites More sharing options...
Sorcery Posted April 3, 2020 Report Share Posted April 3, 2020 On 4/1/2020 at 9:22 AM, Pres said: selections in Hamer A very eye opening read. From Frank Hamer's, A Potter's Dictionary of Materials and Techniques. https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.amazon.com/Potters-Dictionary-Materials-Techniques-Fifth/dp/0812238109&ved=2ahUKEwjnp76qwszoAhXOB80KHUWNDLEQFjAKegQICRAB&usg=AOvVaw2Vr6puVklniNYDq0i1AYXu @tomhumf if your moisture levels are equal, this is your problem. Sorce edit by Min: link to the Frank Hamer explanation here, Figure 7. (Copyrighted material removed from forum) Link to comment Share on other sites More sharing options...
Bill Kielb Posted April 3, 2020 Report Share Posted April 3, 2020 1 hour ago, Sorcery said: A very eye opening read. From Frank Hamer's, A Potter's Dictionary of Materials and Techniques. https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.amazon.com/Potters-Dictionary-Materials-Techniques-Fifth/dp/0812238109&ved=2ahUKEwjnp76qwszoAhXOB80KHUWNDLEQFjAKegQICRAB&usg=AOvVaw2Vr6puVklniNYDq0i1AYXu @tomhumf if your moisture levels are equal, this is your problem. Sorce I tried to get everything oriented like that, mine seem to stay pretty random Link to comment Share on other sites More sharing options...
Babs Posted April 4, 2020 Report Share Posted April 4, 2020 On 4/2/2020 at 2:24 AM, Min said: The speed and amount of time spent throwing the lid and base seems to make a difference in how much it shrinks too. I've found if I throw a shallow wide lid quickly it will shrink more than if I slow down how long I take to make it. I know it doesn't seem logical but I've seen it time and again when I throw lids too quickly. Don't know but on throwing quickly you may not be compressing the clay as much.....just a thought so clay more stretched and it takes up as dries out... Link to comment Share on other sites More sharing options...
Hanoverian Posted July 26, 2020 Report Share Posted July 26, 2020 I too have trouble with lid fit. The lids have a flange and shallow dome and the pot has a plain top. Even though they fit when leather and dry, and usually when bisqued (if not, I sand them to fit). My problem seems to happen during the glaze fire. They are fired separately since the top of the pot is glazed. I make sure the kiln shelf is smooth with no bumps or divots, so both pieces are sitting solidly and not likely to warp due to uneven kiln shelf. Other folks have talked about difference in shrinkage due to size/shape of each piece. Does anyone know of guidelines or tips for calculation for shrinkage due to shape or other tips? Typically the problem I have is that the lid rocks or the flange is too large (too much to dremel), doesn't fit down into the pot, or rocks, Even tho they fit with wiggle (enough for glaze) room when bisqued. Any suggestions, tips, etc.. are greatly appreciated! Thanks! Link to comment Share on other sites More sharing options...
Bill Kielb Posted July 26, 2020 Report Share Posted July 26, 2020 49 minutes ago, Hanoverian said: Any suggestions, tips, etc.. are greatly appreciated! I like to fire them together and leave ample clearance for the potential they could go out of round. Anything thrown with real tight tolerances needs to be very uniformly thrown for me, so it starts round and never deviates. Also remove most wares from the wheel to a simple cfold paper towel on ware board when I can. Bottom doesn't stick and distort the shape and it dries very evenly. No point in throwing super perfect just to ruin it while drying. Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted July 27, 2020 Report Share Posted July 27, 2020 If you’re firing a lid with a flange on the flange rim, it can still warp as the piece shrinks. Min has said before that she fires her French butter dishes separately and the top goes on a clay cookie to prevent such warping. I favour drying and firing lids together with their pots, especially larger ones. I find on the bigger ones you also have to be really mindful of plastic memory when you’re moving lids or trimming them. Link to comment Share on other sites More sharing options...
neilestrick Posted July 27, 2020 Report Share Posted July 27, 2020 If they fit well when dry, it will only take a tiny bit of warpage to mess up the lid fit after glaze firing. And glaze thickness can further mess it up. It's best to fire them together, leaving areas that touch unglazed. If the joint is too rough for your liking after firing, put some 220 grit silicon carbide on the joint with a touch of water, and grind the two pieces together. You'll get a super smooth finish in very short time. Link to comment Share on other sites More sharing options...
elaine clapper Posted July 28, 2020 Report Share Posted July 28, 2020 "is that the domed lid shrinks MORE because it shrinks in a dome shape, whereas the casserole only shrinks in one direction." Thanks liambesaw , I have always been disappointed that my domed teapot lids do not fit tighter. Now I know why and can make adjustments. Link to comment Share on other sites More sharing options...
Pres Posted July 28, 2020 Report Share Posted July 28, 2020 If you find the rough rim, a problem from firing them together, try and old trick. I used to put a lining of Soft Scrub in between the lid and the pot on the rim. Then I would carefully turn the lid on the pot in a back and forth motion for a while to actually polish the rim of the pot, and the gallery on the lid. I also use this technique with polishing compound used on cars with my GG holding the pot while it turns lightly on the wheel with the lid held firmly in my hands. I have been making canisters that have an inner and outer lip on the lid that forms a sealing, not air tight, but bug tight gallery. Not really needed, but aesthetically it looks good. I use this technique on those, and haven't cracked a one. best, Pres Link to comment Share on other sites More sharing options...
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