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jo4550

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  1. Like
    jo4550 got a reaction from Galla in Oil to mix with cobalt oxide and fire over glaze at 800 deg C.   
    Hello Sean
    Welcome to the challenging and perplexing world of ceramics. Fortunately or unfortunately, depending on your mindset, ceramics has not yet reached the stage where instant success can be achieved without prior learning and understanding the complex interactions of the materials that are used along with the complexities of the firing process. Ceramics is an art form using a wide range of skills. Without the knowledge of this craft one is not in control of the results. I am not setting this out as a judgement on your thoughts but rather to help you understand the complexities behind the question you initially posed.
     
    1. The "old Euro style blue on white" commonly known as delft, faience, majolica used cobalt mixed with water and a small %age of flux painted on the UNFIRED glaze surface. The work was then fired to the maturation temperature of the glaze. Today the majority of blue and white ware in this style is achieved by the use of screen printed overglaze decals.
     
    2. When copper plate printing techniques came into being prints were made in the manner you described but were only used on BISQUED surfaces as the porosity of the ware was needed to allow the oil to be absorbed into the surface so that the tissue could be removed cleanly without smudging. This is not able to be done on glazed ware. I have attached a PDF I made from Ceramic colours and Pottery Decoration by Kenneth Shaw. This book is the standard for understanding overglaze. This excerpt fully explains the copper plate process as well as all the problems encountered with its use.
     
    3. As you are aware certain oxides are used to obtain colour in ceramics. It is how these oxides are prepared that allows their use throughout the whole ceramic spectrum. China paints are simply ceramic colour mixed with flux to allow the colour to "melt" onto the fired glaze surface. The proportions of flux to oxide varies according to the requirements of each individual oxide. These compounds are then fritted (heated to melting point and then crash cooled) and then ball milled to the fineness required for use as overglaze. Basically ceramic overglaze colour is nothing more than an extremely low firing glaze applied to a non absorbant surface. This has been well and truly worked out by the ceramics industry which needed consistency of results for their production. The colours (china paints) are then mixed with either oils or water based mediums for use over the fired glaze.
     
    4. The overglaze answer to underglaze tissue transfers are waterslide decals. These can either be screen printed or digitally printed onto decal paper which is really a portable version of the early "bat prints" which used gelatine bats to transfer the colour. With decals the gelatine base is on the paper. You can make your own ceramic overglaze decals using china paints and a medium (oil or water based) and a silk screen or you can print out laser decals using a laser printer. There is heaps of info here in the forum on laser decals.
     
    5. The question of which oil to use depends on the properties you need. There is a wide variety. Following Marcia's suggestion of Paul Lewing's book is a starting point.
     
    6. Tissue transfers are readily available today as they are coming in from China and Japan. The factories I visited in China used engraved zinc plates and used a water based mixture not oil.
     
    7. Overglaze decorating is simply part of the whole ceramic continuum. It has been in use since 1000 AD. Somehow it has been sidelined with the emergence of STUDIO ceramics last century. However today there is a growing awareness with potters embracing this within their oeuvre rather than simply thinking of it as the China /Porcelain painters domain. An increasing number of china painters are turning to pottery techniques to more fully understand the processes involved.
     
    Regards
    Johanna
    Copper Plate Printing.pdf
    Copper Plate Printing.pdf
  2. Like
    jo4550 got a reaction from Marcia Selsor in Duncan Gold Luster Question   
    It doesn't matter what brand of gold or lustre you are using you should not be present in the same space as the kiln when you are firing these.   The toxicity of gold fumes is present till at least 450.C.  You will notice that is when the smell also disappears.   
     
    You should never work in the same space as a kiln  when it is being fired.   Fumes are being emitted all the time.   
  3. Like
    jo4550 got a reaction from charad in is gilding / gold leafing food safe ?   
    http://chinapaintingtoday.com/store Look under Precious metals. I can recommend the Fay Good 12% liquid bright gold. It is a German product. It is the one I use. Another link to gold is
    http://www.thegoodstuff.com/ghlb1.html. This is also a German product. Germany has a history of producing the best gold.
     
    Golds and lustres are best bought from China/Porcelain painting suppliers. I don't know of too many painters who use Duncan products. They are aimed more at the hobby market.
     
    Regards
    Johanna
  4. Like
    jo4550 got a reaction from kathaleena in Are Decals Food Safe?   
    Hello Spring
    I don't know whether this well help you but this is what I know about overglaze decals.
     
    Decals are simply overglaze aka porcelain paint/china paint either screened or printed by computers onto waterslide decal paper and covered with a covercoat.
     
    Overglaze/porcelain paint/china paint is composed of ceramic colour plus flux which determines the firing temperature which in this case is around 800.C (cone 015). So really it is just a very low firing glaze. Traditionally lead has been the source of the flux. Some of the colours contain anything up to 60% flux. Until recently there have been no restrictions placed on use of overglaze colours but now stringent food safe requirements are being put into place as to where the colour can come into contact with food. Colour composition is now changing with the use of boron based fluxes. There is a lot of reformulation happening as high alkaline fluxes change colour responses.
     
    Into this mix then comes the source of the colour. I notice that some of the decals are red and orange/brown. To the best of my knowledge cadmium is involved in theses colours and they will leach in contact with certain foods.
     
    To weigh up your question then I would suggest the following. If the decals are very old stock they would not meet present day food standards. However this should not stop you from using them if you place them where they will not come into contact with food.
     
    Another alternative would be to fire them to a higher temperature to the point where they actually sink into the glaze. They then effectively become inglaze colours. However the rider to that is that you may loose the the red colour as that is very fickle with regards to temperature. Most other colours would not be affected.
     
    Johanna
  5. Like
    jo4550 got a reaction from Stephen in Decal Help Please!   
    Stephen, ceramic toners  will not work in a conventional laser printer.  The printer needs to be altered to accommodate the use of the ceramic toners.  I believe some Ricoh printers are retrofitted for this.   The polymers (plastic bead like substances) adhere the colours to the decal paper.  Mason stains are not milled fine enough for laser toners and they need to be mixed in specific proportion with the polymers.  There are also 2 different systems out for ceramic toners.  One has a flux in the toner mix which allows the decal has at approx 800.C.  The other has a flux in the covercoat which is applied after the printing.  This allows the decal to be fired at the temp required, eg for glass, overglaze or inglaze temps.
    Regards
    Johanna
  6. Like
    jo4550 got a reaction from Colby Charpentier in is gilding / gold leafing food safe ?   
    name='dontstareatthesun' date='17 January 2013 - 09:53 AM' timestamp='1358380420' post='27980']
    The Japanese frequently use this technique.
     
     
    and that would be food/drink safe ?
     
     
    Hello Kennedy
     
    Gold for use in ceramics comes in the following forms:
    1. Powder
    2. Leaf
    3. Liquid as Liquid Bright Gold (different concentrations) and Burnishing Gold.
     
    I have attached a PDF of the relevant section of Kenneth Shaw's "Ceramic Colors and Pottery Decoration" This will explain to you all that is known about gold and ceramics.
    And yes, fired gold leaf is food safe.
     
    I beg to differ with your initial statement that "but after some googling I found out that gold luster is not food safe" I would be interested in viewing your links on this. The other attached PDFs should settle your mind about the food safety of gold as well.
     
    Below is an edited copy of an email reply that I sent to Dinah Snipes Steveni in July 2012 after she contacted me regarding gold and food safety.

    "My first thoughts when I read this are:
     
    Rosenthal uses Liquid Bright Gold and Burnishing gold lavishly on rims of domestic glass and pots and the EEC has the most stringent guidelines for ceramics production in the world. For those of us who can afford it, dentist still use gold for fillings Gold powder/flakes are sprinkled on the food and eaten.  
    Gold is a pure base metal and it is used in overglaze by extracting the salt of the metal through the use of aqueous regis. For LB (Liquid Bright) and burnishing gold it is then modified by adding mediums and solvents to facilitate its application. These burn off during the firing leaving the pure gold attached to the surface of the pot around 800.C depending on the glaze type being used. Gold itself melts at approx. 1060.C and starts to vapourize. Gold is also used as a powder and paste. I have attached 4 PDFs showing the use of gold, the MSDS and CAS# readings to interpret the MSDS. I get my gold from Fay Good (http://interdec-australia.com.au) and I am pretty sure they source their gold from Heraeus in Germany.
     
    You will see from the Fay Good MSDS that all components bar the gold resinate are either mediums or solvents. You can check their MSDS through CAS#. They all burn out, though I must say it is pretty toxic to breathe in the fumes during the firing. After 450.C all seems to burn out and you can breathe the air again around the kiln.
     
    The hysteria that surrounds the leaching with potters is that they don't do the research to fully understand what is going on. The main culprit with leaching is that lead is used as a flux for lower temperatures. If a glaze is properly constituted and fired to its optimum temperature it will not leach but there are too many variables with individuals and companies taking short cuts so that the use of lead frits has been regulated and lead oxide has been banned in the EEC ceramics industry. However many potters don't realize that once the kiln is contaminated with lead fumes it will be contaminated for a long time.
     
    I must point out here that neither gold nor lustres have any lead in their formulation.
     
    With the perceived leaching problems with Overglaze colours potters don't take the trouble to find out all the facts. Overglaze colours(commonly known as China Paints) are in fact just a very low firing glaze. In the past these have been based on lead as the main flux. Because people (both potters and decorators) are notorious for picking their own firing temperature instead of the maximum recommended, the lead is not always locked in. Now regulations have been brought in by the EEC that ware cannot have more than the allowable level of lead in the decoration from where it touches food or liquid so a whole lot of research has been done to find alternatives for lead as a low firing flux. They are now using a boron based flux. I don't know whether that has happened yet in the US. However in China they are still using lead so be careful when buying any overglaze colour that you can't verify its source. If it is not in contact with food then there is no problem in the fired state. The problem lies in its powdered state. Don't smoke and take care with the dust and also food in the studio. Don't lick or chew the brush which surprisingly a good few people do.
     
    Another thought that passes through my mind is that gold is really expensive and the price of the work should reflect this. Why would a potter then expect that a piece with a gold interior should be used? It is easily abraded. For me gold is used to make a statement. It is like the icing on a cake. However if you cut the cake you destroy the icing.
     
    Reading back through this I sense that this sounds very much like a lecture. I can assure you that it isn't. I just get very passionate about all the misinformation that floats around today. I see this as a result of everybody wanting to be seen as an artist without having any basic training or taking the trouble to acquaint themselves with the knowledge about what they are using. Everybody is trying to reinvent the wheel for their own ends but sadly without knowledge the wheels are turning out square."
     
    As I seem to have run out of upload space here is the link for the Heraeus PDF on the use of gold on dinnerware. http://heraeus-preci...china_home.aspx
     
    Regards
     
    Johanna
     
     

    Gold.pdf
    CAS 7440-57-5%20%20 GOLD.html
    MSDS Liquid Bright Gold.pdf
    Gold.pdf
    CAS 7440-57-5%20%20 GOLD.html
    MSDS Liquid Bright Gold.pdf
  7. Like
    jo4550 got a reaction from mregecko in Lusters   
    Hello
    Sweeping statements like the one you have just offered as an answer to a question do little to advance knowledge. Granted lustres are toxic but then so are many other things that we use in daily life. Just check out your cleaning products that are in common use. Prolonged exposure to clay dust causes silicosis and fumes from the kiln are harmful to your health. Does that mean we should all stop using clay? Scaremongering like this has led to the demise of ceramic education as glazes can no longer be mixed in educational institutions. Perhaps in time we will all have to use self hardening clay as kilns will no longer be allowed to be used. Arming yourself with reliable information is the key. Knowledge is all powerful.
     
    For an informed view on H&S for lustre and overglaze refer to http://overglaze.info/?page_id=283 as well as http://overglaze.info/?page_id=525 for "Working with resinate lustres"
     
    Regards
  8. Like
    jo4550 got a reaction from scoobydoozie in How come I can't get decals to work?!?!?!   
    There 2 cornerstones that need to observed when making and using laser decals.
     
    1. Laser decals work on the premise that the toner contains iron oxide in its composition. Whereas most toners use carbon for the black colouring there are still a limited number of toners that contain black iron oxide also known as ferrite. If the image that you can scratch off is not a red/brown/rust colour it is almost certain that the toner does not contain iron oxide. To find out if the toner contains iron oxide google the number of the toner + MSDS and you will find the material safety data sheet for your query. HP have a list of all the MSDS sheets for their toners. To make laser decals the toner needs to contain at least 40-45% iron oxide/ferrite. That being said I assume you are using a HP B&W laserjet to print the decals. There has been suggestions that some “all in one†laser printers will also work, though I have no experience with these or other brands of printers. The problem with using a colour laser printer is that the drum can become too hot for the decal paper and the drum can be ruined by the the decal fusing onto it
     
    2. Laser decals are simply composed of UNFLUXED iron oxide. There has to some way of fusing the iron oxide onto the surface of the fired glazed pot, otherwise it will simply rub or brush off. There are several ways this can be achieved.
     


    a. The most common way is to find the SOFTENING point of the particular glaze that you are using. This is worked out by testing and trial and error. As the composition of all glazes vary there are no hard and fast rules for this. Though there are some starting points:low-fire glaze: c/06 – c/010, cone 6glaze: c/04 – c/1,cone 10 glaze: c/04 -c/6. These are only starting points for testing your glaze as all glaze compositions vary and also it depends on whether you want the decal glossy and fully embedded into the glaze or more matt and degraded in appearance.
     
    b. Another approach is to coat the A4 sheet of PRINTED decal paper with a covercoat containing a small percentage of flux suitable for the temperature you want to fire to. As commercial covercoats contain solvents it might be worth your while to experiment with a water based varnish like the Cabot brand or better still experiment with the acrylic mediums and varnishes used in the art world. Jo Sonja and Liquitex brands are good starting points. The covercoat can either be airbrushed or painted on and then the sheet suspended and drained overnight so an even coat is achieved.
     
    c. Another approach is to apply the decal and before you fire paint the decal LIGHTLY with a liquid flux. This is simply a 50/50 mix of water and methylated spirit/denatured alcohol with a small percentage of flux suitable for your designated firing temperature added. 5%-20% is a starting point depending on the surface quality that you want. However you must source an Overglaze flux if you want to fire around the 750-800.C mark. In my experience normal glaze fluxes will not work.
     
    d. The other option is to put down a layer of overglaze colour or enamel onto the fired glaze. Fire this to 750-800.C. Then apply your decal and refire to that temperature or slightly lower again. As in all ceramic processes it does not always come easily and testing and personalization of working methods is strongly recommended.
     
    The following link http://overglaze.dem...rg/?page_id=420 will give you other potters' viewpoints and working methods with laser decals.
     
    I have attached images 2 different approaches of work fired at overglaze temperatures.
     
    Regards
     
    Johanna


  9. Like
    jo4550 got a reaction from cstoesz in Anabaptist Ceramics Ca. 1550-1700   
    Hello
    My online research of the Anabaptist ceramics tells me that "The ceramics were called faience or majolica, depending on the process used to make it."

    An online search of "faience or majolica" should answer all your questions.
    Johanna

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