.jpeg.e14571b8528e66a7a9c872fd28550125.jpeg)
Min
-
Posts
5,954 -
Joined
-
Last visited
Content Type
Profiles
Forums
Gallery
Posts posted by Min
-
-
Top firing temp can vary between decal manufacture's. If the glaze is starting to soften/melt at the decal firing temp this could be the problem. Also, did you leave the pots to dry for 24 hours before firing the decals? this wouldn't have caused the glaze to blister though.
-
Hi Kayleigh and welcome to the forum!
Could you post a picture of the pinholes/faults and also a link to the type of enamel transfers you are using?
-
3 hours ago, Mark C. said:
and is it sprayed or brushed?
+1
-
21 hours ago, baetheus said:
Lincoln 60 Fireclay Technical Data (Dated 07/09/02):
21 hours ago, baetheus said:Lincoln 8 Fireclay Technical Data (Dated 07/09/02):
This bothers me. 21 year old data.
For what it's worth, I tried out Oregon Red with and without sand from Tacoma ClayArt and had issues with the absorption being much higher when I tested them compared to the posted theoretical absorption. Spoke with the clay tech at Tacoma ClayArt and she said they have been seeing issues with all their bodies that use Lincoln 60 (including the two bodies I tried). I also found fairly large pieces of stone in it. Might consider running it through a screen before mixing it. I asked Gladding McBean for a more recent analysis and just heard crickets.
-
I would use a stiff glaze rather than a fluid one that thins out on edges. Like Bill said though, glazes are brittle so shearing breaks could very well be a factor.
I know it isn't what you asked about but I have been using Gorilla Max Strength Construction Adhesive in Clear for attaching kenzan in Ikebana. It's 100% waterproof and really really strong! This stuff does not move when set, really good stuff. Perhaps that is another option to the epoxy? I used to use epoxy but find it can shear.
- LeeU, JBT and Callie Beller Diesel
-
3
-
15 hours ago, Babs said:
CMC GUM do the same?
MAGMA and CMC gum have some of the same qualities but they are not the same.
Good chart here showing the qualities of many glaze suspenders and additives. What the chart doesn't show is how the glaze applies with CMC vs MAGMA when dipped. The latter doesn't cause the drips/curtaining when used in dipping glazes.
-
10 hours ago, mr_glazy_man said:
The end result is an absolutely marvellous turquoise that fires at exactly 1040c and without a single defect. And, completely and utterly leadfree. The only thing I need to really work out now is how to increase the crazing.
Really good to hear you got the colour you wanted!
For increasing the crazing the simplest thing to do would be to dunk the hot pieces into cold water. Don't know if this is an option with the the scale of work you do?
I was thinking about your suspension comment you made a few posts back. If all else fails there is a product called MAGMA that will suspend even clay free glazes. There are caveats with it though; it isn't widely available (made by Bracker's Good Earth Clays in the US), it thickens the slurry plus it slows down the dry time. I use it now and then, it really works.
-
@Morgan, glad it's sorted out!
-
This is going to be a tough nut to crack. You demonstrated really well the off-gassing of calcium carb though. Looks like the wollastonite turned the colour more towards blue than green which is also interesting. Good testing procedure. I wonder how much stain the glaze could take before loosing the depth of colour you are getting from the copper. Just spitballing an idea, wonder if you used part stain with a higher melting glaze and blended it with your original copper high fritted zinc glaze. Compromise between depth of colour and temp?
-
-
6 hours ago, Benzine said:
It will will either receive an iron oxide wash only, with the possibility of putting clear over top.
Many clears will bleach out iron from the calcium that is present in most glazes. test?
6 hours ago, Benzine said:The slab was perfectly flat before going into the kiln, and was fired on waster coils to allow for expansion and contraction. It was bisque fired to Cone 04.
Negligible shrinkage between bone dry and bisque temps, I agree with Mark about firing it on a thin waster slab for the glaze fire. (made from the same clay, don't need to bisque fire it)
-
7 hours ago, mr_glazy_man said:
i am using glaze calc, but without having limit guides for earthenware (every target formula seems to be for cone 6) it just feels like I’m shooting in the dark.
Limit charts aka Target Formula might not be that relevant given your recipe is bound to be way off them. If you want a couple for lowfire / mid and high fire
here you go:
7 hours ago, mr_glazy_man said:frit form would be better. 3134 has close to 20% calcium, so I could line blend with that.
Yup, I agree, this would be a good choice to start with. It might raise the melting temperature a bit but I have a hunch it won't be enough. I would do the test Bob suggested at the same time with calcium carb plus a little more epk.
If you do go ahead and try this I would suggest doing a double variable line blend with "A" being your recipe above with 90 FZ16, 10 EPK, 5 copper carb and "B" being something along the lines of 80 3134 (we know that will be too high in 3134 but it should work for a blend test such as this), 10 FZ16 10 EPK, 5 copper carb. (could use 90 frit 3134 but there probably isn't any point).
edit: looking at your test tiles again, looks like you could bump the epk a bit? Might look at the numbers with "B" and consider adding a bit more EPK to that. Given it will be diluted with "A" could give it a go with 20 EPK and see what happens. It would be great if you could get something to work, it's a very pretty colour. Is the glaze really slippery like Hansen found when using this frit?
Instead of doing the ratios like in the chart below I would divide it down further given in all likelihood you will need mostly "A" with little "B". Something along the lines of #2 being 9 parts A with 1 part B, #3 being 8 parts A with 2 parts B and so forth until you get to around a 1:1 ratio. (do the test volumetrically)
My guess about your opacity with the copper is there is far more melt fluidity with the zinc frit than the other more opacified looking ones which allows the clean gassing off of the copper carb. Do you have a microscope you can have a look at the more opaque tiles with to see if there are micro bubbles within the glaze?
- Kelly in AK and Hulk
-
2
-
If you already have a base that works at your chosen firing temp/cone then a simple solution would be to use a stain instead of copper. Vanadium blue stains will give you that turquoisey colour. Vanadium is combined with zirconium in stains so the colour might not be quite as crystal clear, depending on how much you use, this might not be a factor.
To keep using copper and get a blue rather than green colour the glaze needs to be very high in alkaline earths with little clay in it. Like you said magnesium will decrease the crazing so that leaves calcium, strontium, barium and then zinc. You already have boatloads of zinc in that frit (I'm thinking that must be one expensive frit) so look to increase the calcium at the expense of some of the zinc. Calcium in the form of a frit would be best for lowfire.
Are you using glaze calc?
-
This isn't a typical subject we get asked about here. Perhaps if you post a few photos someone might know something about them, if not I would contact someone who does appraisals.
-
Hi Carol and welcome to the forum!
What I used was computer paper and a circle cutter punch. Cut out the circle and used the surrounding paper with the hole cut out of it as a stencil. Dipped the paper into water, let it sit a couple minutes then applied it to the leatherhard clay with a damp sponge, let the surface water dry off a little bit then brushed the underglaze on. (porcelain with spectrum underglazes)
-
It's my understanding that the cadmium inclusion stains are all made offshore in India or China due to environmental regs in other countries. Where Mason gets their Cd stains from compared to the unbranded ones from US Pigments or other suppliers isn't something I've read about. I don't have enough experience with Cd stains to make a comparison.
-
Did you solve the massive crazing issue you were having?
As a test I would suggest prepping the clay by doing a spiral wedge on a dozen or so chunks of your standard 1 lb weight then turn them on their side (so the spiral is not face down) when placing on the wheel head. See if that makes a difference.
-
20 hours ago, mr_glazy_man said:
What material could I use to raise firing temperature of a crazing glaze?
How much do you want to raise the firing temp by?
Have a look at the melt fluidity tests done with Fusion FZ16 as it compares to other frits in this link. It softens and starts to become fluid at around 1500F and by 1650F has run right off the fluidity tester. If you are looking to raise the firing temp by a few cones I would swap out some of the Fusion FZ16 for Ferro 3110. Should be able to do a line blend of the two and find a balance. Ferro 3110 is more than likely to retain the crazing you want to keep.
Image below from the above link from Hansen.
-
Hi Niraja and welcome to the forum!
Have a read through of this thread, @Magnolia Mud Research has a really good post on using soda ash as a wash.
-
After you wedge the clay how are you prepping the mug weights of clay before throwing? Are you placing the spiral of the wedged clay face down on the wheelhead or turning the lump of clay on it's side? Or wedging a large mass then cutting pieces off and patting them into shape before throwing?
-
I've had this happen a couple times if I really empty the pugger on the previous batch the following batch can take ages (like 10 minutes) to get it to feed through. If I look at the end of the barrel I can see the clay going around and around but it won't push through straightaway. As long as the pugger is switched from mix to pug and the auger is going the right way it will work as long as the chamber is full or nearly full. (I have had the same stainless model for at least 10 years) Try leave it on for longer and see if that works.
Welcome to the forum!
-
I'm sorry for your loss.
Museum putty would be a good choice. It holds well but is easily removed. Like this https://www.amazon.ca/Quakehold-88111-Museum-Putty-Neutral/dp/B0002VA9NA
-
Glad it helped!
-
Have a look at this post, @GreyBird had an analysis done on her found clay from along the Hudson River. Page 1 of that thread has the data she recieved, on page 2 she posted where she got it done, https://www.minerallabs.com/. At the time it was $500- for the three tests she had done.
Gerstley and EPK
in Clay and Glaze Chemistry
Posted · Edited by Min
Was it credible noise?
If you do a search for GB on Laguna in California webpage you get "No results for Gerstley Borate (https://www.lagunaclay.com)" Sold out would be the logical assumption but then again we've been down this road before with GB. Given all the alternative sources for boron that have become available since the last time GB became unavailable there shouldn't be too much trouble sourcing other materials to supply boron.
edit: @Mark C., since you have Laguna Distributer status could you ask them if GB is well and truly finished?