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Drying Time


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I noticed this on a post in business from TJR:

 

Paul;
If you jump on your wheel now and get throwing, you could probably pull it off. Think a week for drying, then bisquing, then glaze fire.
I made a series once of "Divorce Pots"' for a Valentine sale. They were slab vases that fit together. If you split up, each of you could take one. They were done in Majolica reds. All sold. Don't ask me why.
TJR.

 

And would love some input on drying time, specifically rushing it. I am crunched for time and plan to throw mugs one day, trim and dry for a day, day and a half then candle a few hours and bisque. I'm in Dallas/Ft Worth and the weather is a nice dry 75ish during the day and most days sunny. Figured would put ware boards out in the sun toward the end.

 

My first xmas show is on 3rd/4th and figured whatever I throw this week and maybe even up through tuesday next I could maybe pull out running kiln right up until that Friday. 

 

In the past have always just waited till things are bone dry and push through and I guess it was often a week.

 

Would love some input. 

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I have managed to pull mugs off in the timeframe you mention. Platters would be a different story, as would anything with a lid that you dry together with the pot. I do not have the benefits of your balmy temperatures right now.

The trick is evenness, not speed. If heavy industry can speed dry a toilet, you can probably push mugs in 3 days.

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I believe you can also do candling if your pieces are not fully bone dry by then. It is keeping the kiln below boiling point (so the water in the greenware does not cause cracks or explosions). I read that 6 hours is good for most pieces, but longer if you have thick wares.

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I work in one week turnarounds this time of year-since its the rainy season my natural gas heater is always on cooking the pots. Last week was in the 70's so I got to have some dry outside. I use porcelain and it dries fast

platters take about 3 days-I throw the largest stuff on Tuesdays while firing the car kiln-working down to the smallest fastest drying stuff.All mugs are covered 1 night after handling then forces dry in the heater.As soon as the bolts are trimmed they are heater dried-shop is in the 70-80-and 90s at the end. Not place for comfort but it works well. Bisque on Saturdays or Sundays unload and wax Sunday or Monday. Monday glaze and laid -Tuesday fire and start cycle over again.

Unload glaze fire thursday or Friday while working on greenware production. Been doing this for many decades-never blowing stuff up-you candle wet pots overnight.Gas kilns -I put really wet pots in an electric as the control is so fine one can do this as long as the handles face away from elements.

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  • 2 weeks later...

I have some drying questions.  It's been between 40 and 60 in my workshop lately, with varied humidity as well, and  I know the key is even drying, but what exactly does that mean?  If I took some things inside the house would that screw them up since they started drying at a lower temp?    I'm careful to seal up  recently "handled"  mugs for a few days so the clay can even out.  I'm wondering how others handle this

 

How can I tell when the clay is dry enough to bisque?  There's the color change, but since it's cold out there even dry stuff feels cold to the touch.  I try to cover rims since they dry faster, but is this necessary on bowls or just on slab plates?  ( I haven't tried plates on the wheel yet).   I try to turn bowls and mugs over regularly so the bottoms get air too, and then move them to wire shelves when they won't pick up impressions anymore.  I generally do some sort of preheat, but for my next load I think it might be more of a necessity than a just-in-case thing, since I want to get it bisqued asap.

 

Thanks for your input and suggestions!

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Just to update, I ran a load of not bone dry to some closer than not toward leather hard. I candled for 10 hours and then slow bisque and did not have any cracking or warping. I was very happy as some pieces were only 1 day removed from trimming and it helped a lot in turn around for the next round of glazing.

 

Irene I have a rolling bun pan rack with zippered plastic cover that I got from a restaurant supply house for $120 with plastic cover and put handled mugs in there for a day and then just let them dry bottom up. Those that I candled were not completely bone dry and some spoon rest were almost leather hard and the 10 hours candling worked great. I don't cover bowl rims but after I trim the all around thickness is close to the same. I cover mug rims pre-handle because I need that part to stay leather hard until I handle. good luck! Maybe try it with a few not important pots and see how it works for you. Keep a log and then just follow the routine that works. I'm thinking of backing off to 7 hours of candling if past leather hard and see if I have issues.  

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I have been leaving my drying pots in a room with a ceiling fan on low.....now that it is cold, I put a little heater in there ......So far, it has been working to do that this fall and now into the winter.  I think the fan moving the air is helping.....it has definitely hastened the drying process. 

 

Roberta

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 Stephen, a rolling bun pan rack is genius!  Lots of room and adjustable shelves too...   I'm using a 3 shelf, five foot high metal shelved plastic covered greenhouse that I dragged in from my garden, and it works pretty well, except that it only has 3 shelves.  I'm definitely going to look into finding a bun rack, it will have a smaller footprint than what I'm using too.  And it sounds delicious  :rolleyes:   

 

As for thin, evenly thrown pots, Neil, define thin.  1/4"?   I'm working on evenness as well as thinness.  If I put pots in my zip-up rack for a day then open it up for another day and then preheat for 10 hours?  It just seems that things are drying much more slowly now that it's cooler out, and as it's been raining all day today I feel like I'm losing ground.  Some bowls I threw yesterday late afternoon aren't ready to be trimmed yet and it's 26 hours later.  Marcia I'm sure NJ humidity is summer rivals that of southern Illinois, and right now in November it seems to be just as bad.

 

Well.   I'm going to trim those last pots, hopefully tomorrow,  wait a couple days and then put one of them in the kiln along with stuff that's more dry, and candle for 10 hours and then slow bisque.  Or maybe I'll go wild and try 2 pots!  Can I assume that having the vent on while candling will help pull out the humidity?   

 

Thanks everyone, I'll keep you posted.

 

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i know some of the classically trained potters think i am crazy for using my oven to dry things.  it works if you only have a few items, there are only two shelves in the oven.  the lowest temperature it will hit is 170 degrees F.  it is enough to dry stuff that has been sitting on drywall sheets overnight.  leaving it in there for 20 minutes dries it enough to allow handling to wipe a damp or wet sponge around the sharp edges to soften them.  done, until glaze is sprayed on that greenware later in the day.  turnaround less than 24 hours from blob to kiln shelf.  this is only in an emergency when i should have made them last week and did not.

 

my work is slab rolled and thin, less than a quarter inch.  my bowls are made without a huge wad of clay at the bottom when set aside from the wheel.  i trim all of it while on the wheel and remove it on the small bat without cutting it off.  the last bit of trimming and footing is done when the pot dries enough to pop off the bat.  i have put both bowl and bat into the oven for 15 minutes at 170 and the bat comes away without totally drying the pot surface.  it is very easy to trim that bowl and even some that might have become too dry.  

 

part of what makes this work is that i have thoroughly experimented with this particular clay.  i know how wet it can be and how to dampen it enough for a trimming tool to do its job if it is the last of a series and might have gotten too dry.  (Chilly, there is that americanism)

 

anyway, sometime you wonder what you might do today, try the simple tricks of learning how your clay works in all situations.  and try stuff, think it out and ask what is the worst that can happen?   it is only clay.  but that is on an ordinary day.   sorry, stephen, this won't help you get things finished for a quick sale but might set some new person off on some experiments.

 

why do we bisque?  there are reasons for individual situations but is it only a habit you were taught in a shared situation that no longer exists?

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Oldlady - "it is only clay" how many times have I heard you tell me this? It only take a few dozen times before I actually HEAR it and try whatever it is you are trying to get me to do!

 

"It is only clay" doesn't sound scary at all, it sounds simple and it the point. I really should listen to you when you say it more often rather than listening but not hearing. Do you think I will ever be able to do that or am I just too stubborn, having to know the why why why of everything you say.

 

"It is only clay"

 

T

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oldlady i am a little confused. do you do some slab built bowls and some wheel thrown bowls, or do you put your slab built bowl on the wheel to trim? 

 

boy am i discovering the importance of evenness. i am a student. i throw at school and handbuld at home. i cant believe how many of my handbuilt bowls (pinch with coils, then sureformed and ribb trimmed and therefor not as even as wheel thrown bowls) have cracked. simple air drying with no cover. or have fine cracks. i've learnt to identify the bisque sound which tells me which pots have some sort of cracks which i can see or not.

 

so i covered them overnight and then air dried them. that extra 16 or so hours of covers really took care of the cracks. 

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I ended up bringing in 10 drying pots and 4 I'd just thrown and putting them on racks on my dining room table with the overhead fan on.  When I came back 5 hours later things had dried amazingly well - too well in the case of the new stuff.  I had to use my ginsu knife to cut them off the bats since I couldn't wire them off.  Caught them just in time.   I sprayed the bottoms with water a couple times, covered them and let them sit a bit and was able to trim them fine tho.  And it made me realize I've been trimming too wet. 

 

I also realized a number of other things I need to specifically work on, and for these I have you all to thank for various bits of information large and small in all your previous posts.  And I do thank you.

 

It turned out I had enough for a bisque load without those most recent bowls, so I'm saving them for the next load, which will be sooner than I expected now that I know some new drying techniques and have a new awareness of the importance of even thickness.  

 

Oldlady, what small bats do you use that the pots pop off at the right time?  I use Wonderbats and they're great, but you have to wire off the pots.  

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Oldlady, what small bats do you use that the pots pop off at the right time?  I use Wonderbats and they're great, but you have to wire off the pots.  

 

Just to chime in, Not sure what the system is called but my ex used the singular bat with square cutouts and bought 30 of the cutouts for all things small and she loves them. They pop off the bat when ready to trim, never seen here have to wire them off and when she throws 20-30 mugs or vases and the like they fit very tightly in the drying racks taking up very little space. I use the square plastic ones for the same forms for saving drying space but more often than not have to wire off so I'm thinking of switching.

 

I know many do not dry on bats and place on ware boards right after throwing but I simply got so tired of warping and other wise distorting several of my forms per batch by handling them right after throwing. I am working on throwing dryer and may give it a second shot at some point. It was really nice to just plop them on ware boards and then just turn as needed and grab and trim.

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I was just looking up bat systems and there are a number  of them.  Even tho my Wonderbats have to be wired off (and if you wire them right after throwing away you'll have to do it again later anyway cause they re-stick), I still like the ease of the system.   Sure beats all the deformed pots I was getting sliding them off a wet wheel.  And they're pretty reasonably priced compared to lots of other bats.

 

I'm going to go check out some of those other systems now.

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