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Sgraffito and safety question


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Hello,

I do a whole lot of sgraffito work (black underglaze on white clay) and am growing more and more concerned about the dust it generates as I work. I aim for 'cheese hard' as the perfect time to sgraffito which is great to start but there are times when it takes me over an hour to complete a piece and by that point the piece is much drier which means more dust!

So I have a couple questions here...

Is there a way to keep the part of the piece (bowl, platter etc) that I'm not working on from drying out while it waits for me? Would keeping it wrapped with plastic be any help at all? I'm not even sure how I would do that effectively!

How do you deal with the scraps? I have been using a brush and a trash can which I'm sure isn't a very good idea. I've read in this forum that some people use a 'drop cloth' of various kinds and to go outside to shake it out, which is a great idea but I live in the Midwest and right now it's pretty darn cold to do that. I do have a HEPA vacuum.  Would that be a solution?

Also, in terms of a respirator. I pulled out my old one (P100) only to discover it doesn't fit that well anymore. So, as a small woman I would appreciate your guidance, advice and/or recommendations as I look to replace it.

Thanks!

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There are some options when working with a long term sgraffito on pots. One would be to continue to dampen the pot with a mister bottle as often as needed. Another would be to use a sealant of some sort to hinder the drying process of the pot, a spray wax or enamel.  You may find that this opens up other possibilities as there are some colored waxes out there, Maybe you could use the colored wax in areas, and sgraffito through that. 

As far as cleanup, you are correct to be concerned about silica dust, and again there are some possible solutions.  You could use a damp cloth on the work table under the piece to gather the bits of clay and dust, when done wrap the cloth up, and let sit until you can shape the dampened pieces into a lump and remove to throw out or re-wedge. Another possibility is a frame over a large bucket with water in the bottom for the clay to fall into. A mask is useful, but only if it fits and is comfortable to use while working.

Hopefully, this little brain storm will help you to come up with your own solution.

 

best,

Pres

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I live in humid florida and don't seem to have the problem of ware drying out in just a couple of hours of carving so maybe running a humidifier while carving might stop the drying out.

i find carving over a shallow tray like a large cake pan catches all the crumbs from carving and can be disposed of later either in the slurry bucket or trash.

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Hi  Pres,  PSC and Min

Thanks for the good suggestions.

I like the idea of dampening via misting but am concerned about the effect that would have on the under glaze. Will it get splotchy or spotty? Would I mist on the surface being sgraffito-ed or the back side? What is enough/too much?

I wonder if I could create enough humidity to dampen the clay by simply placing a wet sponge of cup of water along with the piece, wrap it well  in plastic and give it some time?  Would that have any effect?

I'm intrigued by the suggestions to slow the drying process down. Believe it or not, I do have a bottle of Forbes wax but I'm not really sure I understand how to do that. Would I apply it to the entire piece front and back? I assume it burns off in the bisque fire, right?

I like the damp cloth idea. I will give it a try. I'm still worried/concerned about the bits that don't necessarily 'fall' off the piece when I turn it upside down.... there are always little bits that get stuck and require a brush to clean them off. I guess this is where the good mask comes in handy!

Thanks again, Andryea

 

 

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2 hours ago, tinypieces said:

I wonder if I could create enough humidity to dampen the clay by simply placing a wet sponge of cup of water along with the piece, wrap it well  in plastic and give it some time?  Would that have any effect?

I'm intrigued by the suggestions to slow the drying process down. Believe it or not, I do have a bottle of Forbes wax but I'm not really sure I understand how to do that. Would I apply it to the entire piece front and back? I assume it burns off in the bisque fire, right?

If you don't finish the piece in one session I would use a damp box. (it's just a plastic bin or tote with a tight fitting lid that you pour plaster into. Once the plaster has cured you place your piece(s) in the box and the damp plaster keeps the pot from drying out.) Don't use the plaster too wet or you can get water splitting of the pots. (been there done that)

Re the Forbes wax, it's going to depend on how thick and how dry the pieces get while you are working on them. It's not going to hurt to do both inside and out with it, yes it will completely burn off during the bisque. It's expensive for me to order in Forbes, I don't know if it is for you too? You could use Forbes on the underglazed part and a less expensive wax on the non-underglazed part to save some money.

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13 minutes ago, Min said:

If you don't finish the piece in one session I would use a damp box. (it's just a plastic bin or tote with a tight fitting lid that you pour plaster into. Once the plaster has cured you place your piece(s) in the box and the damp plaster keeps the pot from drying out.) Don't use the plaster too wet or you can get water splitting of the pots. (been there done that)

Re the Forbes wax, it's going to depend on how thick and how dry the pieces get while you are working on them. It's not going to hurt to do both inside and out with it, yes it will completely burn off during the bisque. It's expensive for me to order in Forbes, I don't know if it is for you too? You could use Forbes on the underglazed part and a less expensive wax on the non-underglazed part to save some money.

Here in the US it's under 30 a gallon

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That's the one we use as well, comes in medium, small, large; here's the small'n

3M™ Half Facepiece Reusable Respirator Assembly 6191/07001(AAD)

https://www.3m.com/3M/en_US/company-us/all-3m-products/~/3M-Half-Facepiece-Reusable-Respirator-Assembly-6191-07001-AAD-P100-Small-24-EA-Case/?N=5002385+3294759262&rt=rud

The pink fabric discs breathe well, imo (spent a significant portion of my working life wearing a respirator).

Good tips, thanks - have tried spraying work with a mister, which does work, however, a bit too much too fast is to be avoided, haha; a light, fine mist, wait for it to be absorbed, wait, a bit more mist, etc. Hence, looking forward to trying the wax resist.

 

2091.JPG

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tiny,  are you using slip or underglaze as your color?  it sounds like underglaze.  the bits you cut off can be turned into slip for recycling instead of tossing it out.    

if you work on a terrycloth towel, you can dampen it to keep the bits from shifting around when they land on it.  to keep your lap or work surface dry, put a dry cleaner plastic under the towel.   a small fan over your shoulder will direct the bits downward onto the towel.

but, frankly, i think this is not a serious problem.  i cannot imagine a single person working in a studio making enough dust to become a danger.  wax sounds like a $1000 solution to a 50 cent problem.  wear a respirator and just mist a little if you really have to.  

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Thanks Min for the reference to the damp box. While I like that idea I'm not so keen on dealing with the plaster part and I'm not really sure I understand how the plaster will stay damp once it cures. What am I missing? I wonder... are there any other ways to create a damp box?

Thanks old lady, I wasn't sure what to do with the clay that had under glaze on it which is why I've been tossing it but now that you suggested making slip out of it, I'm gonna give that a go. I also appreciate your level headed-ness about the severity of the problem. I'm pretty good about keeping the dust down by damp wiping the surfaces and floor. But I was beginning to freak out a little because of a persistent cough I've had for a while now. I know it's not my lungs (they're clear) but I just have this crazy post nasal drip and wonder if it's aggravated by the dust from the sgraffito.

And a big thank you to everyone else  who chimed in. I did buy myself two new respirators (just in case) and spare filters. Plus, a HEPA air purifier for my studio. It may be overkill but I'd rather be safe than sorry! Besides, I don't want what I love doing to kill me at this point in my life! lol.

 

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6 hours ago, tinypieces said:

Thanks Min for the reference to the damp box. While I like that idea I'm not so keen on dealing with the plaster part and I'm not really sure I understand how the plaster will stay damp once it cures. What am I missing?

@tinypieces, video below showing how to's and why's of a damp box. (includes how to mix up the plaster)

12 hours ago, oldlady said:

wax sounds like a $1000 solution to a 50 cent problem.  wear a respirator and just mist a little if you really have to.  

Wow, and here I thought my wax was expensive! ;) If misting works over underglaze then wonderful, my underglazes (mostly Spectrum) have enough binder in them that misting doesn't soak into the clay very well though.

 

 

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Thanks for posting the video Min and your encouragement/support Chilly. I'm a visual learner and it answered a lot of questions and cleared the confusion up.  My only concerns now are that the size of some of my pieces get to be 12" in diameter which would require a fairly large box and a place to store it. I wonder, too, can I use any kind of plaster? He didn't say anything about that. Other than that I may give it a try. It really appears to  be an extremely effective solution which I don't get with all the other methods (misting, wrapping it in plastic etc). I sounds like that method will produce the reliable and consistent results I'm looking for. Thanks again :)

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1 hour ago, tinypieces said:

Thanks for posting the video Min and your encouragement/support Chilly. I'm a visual learner and it answered a lot of questions and cleared the confusion up.  My only concerns now are that the size of some of my pieces get to be 12" in diameter which would require a fairly large box and a place to store it. I wonder, too, can I use any kind of plaster? He didn't say anything about that. Other than that I may give it a try. It really appears to  be an extremely effective solution which I don't get with all the other methods (misting, wrapping it in plastic etc). I sounds like that method will produce the reliable and consistent results I'm looking for. Thanks again :)

I put home depot plaster in the big black Costco bins, works great.

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I bought a container that holds rolls of Christmas wrapping paper on closeout,  it would easily hold two platters.   There are some buckets that you can buy that are for summer activities  that would hold one platter and easy to move around.   You may not be able to find them until summer gets a little closer.    Denice

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four comments on keeping in progress items moist:

1.  I wrap my leather hard work with several layers of 'cling' type plastic wrap (aka Saran wrap); the plastic is pressed tight against the clay to prevent uneven dry spots. I then loosely  wrap  the item with the same plastic I cover stuff for overnight storage. I once kept a large 12in tall leather hard vase for a summer and two semesters before finishing the sgraffito work - the vase was a little bit drier, but was still leather hard.  

2.  I made hand impressions in soft porcelain slabs from Nashville back to Texas with each slab wrapped tightly in Saran wrap placed in side a zip-lock plastic bag that had been sprayed with water in the plastic bag.  They were kept from June to November in a closed Zip-loc plastic box.  They slabs were still flexible enough to shape into cups. 

3.  I often store wet ware in a tight fitting plastic box which has a small cup of water also in the box, or with the ware sitting on a brick or shard to keep off the bottom.  They will stay wet for weeks if the water doesn't evaporate from the cup.  One bowl was stored in a bucket for over a year at the wet stage. 

The approach in comments 1 & 2 is to minimize the amount of air between the ware and the plastic to an minimum; the air breathes as the temperature rises and falls from the initial wrapping; when the breath press is outward, the air cares out some moisture away from the ware.  The compressing the wrap against clay surface minimizes the volume changes with temperature changes.  The second outer wrap also lowers the drying by providing additional barriers that the moisture must pass before being lost to the ambient environment. 

The approach in comment 3 is similar but as the container breathes the water in the air is replaced from the source of liquid water in the open cup/bottle. As long as there is liquid water in the open cup/bottle, the moisture in the air is in equilibrium with the water and with the ware.  

4. Consider under-the-bed clear plastic storage containers for storing plates in progress.  

LT

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At the local JC ceramic lab, other students use/used plastic to keep work wet until the next class, but deformation, sticking, and other oops - the time window being so narrow - drove me to look for other solutions, ended up collecting plastic containers to invert over the work (on a bat). In a common environment, a few blobs of clay to hold the container in place provides some jostling protection. Over a long weekend or holiday - especially in hot weather - a bit of wet sponge in there, as in #3, above.

I like the wet box idea, however, may never get 'round to it, as the inverted containers are working for me, and also allow for individual drying rate control ...and choosing when to wire off as well.

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On 1/27/2020 at 3:09 PM, Stephen said:

I can't imagine sitting around for hours on end wearing a respirator. I wear one for glaze mixing and that's annoying enough. 

I couldn't agree with you more and I don't even mix glazes! Honestly, just cleaning my (in my spare bedroom, home studio) is enough. For this I'd wear it. Plus I just bought myself a HEPA air filteration unit for the room.

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On 1/26/2020 at 4:36 PM, Magnolia Mud Research said:


four comments on keeping in progress items moist:

1.  I wrap my leather hard work with several layers of 'cling' type plastic wrap (aka Saran wrap); the plastic is pressed tight against the clay to prevent uneven dry spots. I then loosely  wrap  the item with the same plastic I cover stuff for overnight storage. I once kept a large 12in tall leather hard vase for a summer and two semesters before finishing the sgraffito work - the vase was a little bit drier, but was still leather hard.  

2.  I made hand impressions in soft porcelain slabs from Nashville back to Texas with each slab wrapped tightly in Saran wrap placed in side a zip-lock plastic bag that had been sprayed with water in the plastic bag.  They were kept from June to November in a closed Zip-loc plastic box.  They slabs were still flexible enough to shape into cups. 

3.  I often store wet ware in a tight fitting plastic box which has a small cup of water also in the box, or with the ware sitting on a brick or shard to keep off the bottom.  They will stay wet for weeks if the water doesn't evaporate from the cup.  One bowl was stored in a bucket for over a year at the wet stage. 

The approach in comments 1 & 2 is to minimize the amount of air between the ware and the plastic to an minimum; the air breathes as the temperature rises and falls from the initial wrapping; when the breath press is outward, the air cares out some moisture away from the ware.  The compressing the wrap against clay surface minimizes the volume changes with temperature changes.  The second outer wrap also lowers the drying by providing additional barriers that the moisture must pass before being lost to the ambient environment. 

The approach in comment 3 is similar but as the container breathes the water in the air is replaced from the source of liquid water in the open cup/bottle. As long as there is liquid water in the open cup/bottle, the moisture in the air is in equilibrium with the water and with the ware.  

4. Consider under-the-bed clear plastic storage containers for storing plates in progress.  

LT

Thanks @Magnolia Mud Research for all that fantastic information and easy solutions. I love learning how air breaths along with our pots! I'm excited to begin implementing these techniques. Andryea

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