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jo4550

Member Since 08 Sep 2010
Offline Last Active Jul 02 2014 05:58 PM
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#58692 Decal Help Please!

Posted by jo4550 on 17 May 2014 - 01:16 AM

wish I could find out more on ceramic toners. There seems to be a company in China that is shipping them but they have no prices or ordering routine setup and calling china seems daunting and possibly confusing. 

 

A few companies package them together with printers offering an expensive 'system' but it really just seems that one could use a mason stain/materials mix that can be put in a color laser printer cartridges.

 

Just not sure what that mix would be to make it fuse to the decal paper. The systems also show them spraying a clear coat over the decal before putting on pot. 

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




#34112 Newbie questions about firing and mildew

Posted by jo4550 on 05 May 2013 - 01:51 AM

Hello Sue
What you are describing is quite prevalent in refiring glazed ware at at China paint temperatures. It is often called mildew but it is actually black spotting that occurs on the UNGLAZED surfaces when the clay body has NOT been fired to full maturity. Hence you will normally find it under the work (where it touches the shelf)and footrings. It is not trapped carbon from poor bisqeing. It is mostly found in older pieces that have been around a while. It is carbon being trapped in the open pores of the body and this can be generated from a variety of sources.

The carbon can become reabsorbed and trapped from the media being used so it is more prevalent to occur from oil based mediums than water based mediums. This coupled with poor circulation and ventilation in the kiln during firing allows the pores of the unglazed clay surfaces to reabsorb this new carbon. This carbon can be burnt out with repeated firings especially if the temperature is raised slightly higher. The easy answer to all this is that if you are making things from scratch make sure you fire to the full maturity of the clay or otherwise get a clay that vitrifies at the temperature you want to fire to. Then this problem shouldn't occur. Always make sure you have the lid or door of the kiln slightly ajar in the overglaze firing until at least 650.C This allows the gases generated from the mediums to be dispersed. Always allow plenty of space between the shelves in the kiln during an overglaze firing. Always try to fire to the highest temperature in your overglaze firing depending on your glaze type. eg if using porcelain fire to 800-820.C rather than the lower 760-780.C option. This allows more carbon to burn out. If at all possible fire your pieces lifted OFF the shelf by little wads or pins.

I have attached a small .pdf made from page 125 of "Ceramic Faults and their remedies" by Harry Fraser. This deals with this topic in greater detail and it saves me from having to type it all out.
Attached File  Black spot.pdf   492.53KB   27 downloads

Regards

Johanna


#28063 is gilding / gold leafing food safe ?

Posted by jo4550 on 18 January 2013 - 02:14 AM

name='dontstareatthesun' date='17 January 2013 - 09:53 AM' timestamp='1358380420' post='27980']
[quote name='JBaymore' date='16 January 2013 - 07:20 AM' timestamp='1358338814' post='27940']
[quote name='jo4550' date='15 January 2013 - 06:14 PM' timestamp='1358291688' post='27914']
Genuine gold leaf can be fired onto the surface of the fired glaze.[/quote]
The Japanese frequently use this technique.
[/quote]

and that would be food/drink safe ?
[/quote]

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



Attached Files




#14502 How come I can't get decals to work?!?!?!

Posted by jo4550 on 04 March 2012 - 09:16 PM

I have tried to get decals to work and having troubles...can anyone help?
I bought paper from a Florida Company and they swear you can fire it to cone 06 without it burning away but...
I printed with an HP laser printer a black image and it started to disappear after 700 degrees and if I pull it out at that point the image just scratches off anyway.
Anyone have an idea how to get a decal to fire "permanently" onto a galzed piece?
I would SO appreciate it!


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

Attached Thumbnails

  • Family shot 1952.jpg
  • PFH:All our actions.jpg



#8725 Are Decals Food Safe?

Posted by jo4550 on 19 September 2011 - 06:55 PM

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


#6047 Anabaptist Ceramics Ca. 1550-1700

Posted by jo4550 on 20 April 2011 - 04:53 PM

Hi, I am looking for information on the Anabaptist ceramic industry in Europe ca. 1550-1700 centred in Moravia and Boheimia. At times also known as Habaner ceramics. Some of the descendants of these people live in the USA and Canada and are known as Hutterites. These Anabaptists They created new styles and techniques which I am interested in. I am coming at this from a history perspective as I have no experience in ceramics myself. I would be interested in knowing details about what these techniques were. They began using different materials to produce different colors, so what materials would have been used? Characteristic colours for the glaze were blue, white, yellow and green. For the decoration they used yellow, green, violet, blue and black they used for contour. in the 1600s Where did they get these materials from? How did they fire the items? I would be open to advise, or direction to books, journals or other experts in the field. Thanx for your help!


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



#5485 Lusters

Posted by jo4550 on 04 March 2011 - 06:20 PM

lusters are probably the worst thing you can do to yourself. they are highly toxic and can cause you cancer or worse. personally i would stere clear and toss them. if you are interested in metallic such as the luster gives you i would say investigate raku or another fun way of firing crystallines.




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