Your Best Guess On Overglaze/Lustre Technique

[LauraAnna]

Two-part question:

 

I'm a semi-noob, but avid learning/researcher/student. I'd like to replicate a procedure posted by another kind user here using an old light diffuser grid as a press mold to make tiny mosaics. Her prototypes turned out beautiful. Since my intended use is wall tile, I understand it's best to use ^6 clay. This means I also need to glaze at compatible ^6 level as well, correct? So far so good. Ultimately I'd like to finish with a mother of pearl overglaze/lustre. Now it gets interesting...

 

I fell in love with a lustre effect I saw on a boutique tile. (Nothing easy is as much fun, right?) I found this tile in the store but they don't make tiny sizes and besides, it's crazy expensive (pic attached). The appearance is a creamy base color with a heavy rainbow iridescence and they call it their "metalics" line. In the pic below it almost looks mirror-like but not so much on a single tile. After everything I poured over on this site I am starting to suspect this possibly was fired four times -- third time for some kind of white gold or platinum metallic lustre and then a fourth time for a mother of pearl/opalescence (??) or maybe just MOP?

 

Your guess???

 

Second part -- I found Duncan Mother of Pearl Lustre Overglaze and would like to try it (or anything else equivalent that you can suggest). Many of you say the MOP can be applied over mid fire glazes, and fired for 3rd time at very low ranges (ie. ^018). With that in mind, it sounds like this can be applied over a ^6 glaze provided that it is fired at the mfgr recommended ^020. However, the Duncan website lists something I find somewhat confusing - specifically step #1 & #2.

 

Here are their instructions

1. Apply an overglaze compatible glaze to cone 04 bisque.

 

2. Fire to cone 06.

 

3. Do not stir or shake overglaze.

 

4. Place a small amount of overglaze on a glazed palette:

 

a. For a swirled look, swirl on one coat, overlapping strokes.

 

b. For a smooth look, brush on all strokes in the same

 

5. Correct application should produce a light blue tint.

 

First off, what is a "overgalze compatible glaze"? Secondly, are they saying I need to apply a glaze to the bisque with a glaze that only fires to ^06? That would mean I'd have to use a low fire ^06 clay (?) Surely they are not saying I should fire the lustre to ^06 -- everything I've read on this forum says that's too high and would burn off. Does this mean I cannot use Duncan Mother of Pearl over a ^6 clay fired with a ^6 glaze? If not - what then do you recommend for Mother of Pearl on cone ^6 glaze? Or can that even be done?

 

thanks so much for reading!

[jo4550]

There are a couple of issues here but I would like to start off by pasting an excerpt from the Heraeus fact sheet on Lustres as I have run out of space to add any more attachments. This can be found in its entirety at http://tinyurl.com/lvt6m7c

Heraeus is one of the largest overglaze and lustre producers/suppliers in the world. They are based in Germany.

 

 

 

1 General Information

Lustres are based on metallic compounds dissolved in organic solvents. After firing they form a very thin layer (less than 0.1 μm).

Typical characteristics of lustres are their brilliance as well as their metallic iridescent brightness which occurs after firing on smooth substrates.

The lustre loses its iridescent effect on matt surface and appears matt.

Lustres are suitable for the decoration of glass, porcelain, bone china, earthenware

 

2 Firing Range

480-630° C / 896-1166° F for glass and lead-crystal.

650-900° C / 1202-1652° F for porcelain, bone china, earthenware and tiles.

 

3 Precious Metal Content

Lustres contain less than 6 % precious metal or are precious metal free.

 

4 Properties

4.1. Mechanical Resistance

The mechanical resistance of lustres does not achieve the same standard as most

ceramic colours and precious metal preparations because the formed lustre film is

very thin. Therefore, we recommend that customers test the decorations under

their own conditions to achieve the required resistances.

 

From this excerpt you will see that lustres applied to tiles used as a splash back may be a short term measure as constant cleaning with an abrasive will soon wear off the lustre.

However I am assuming that you have taken this into consideration.

 

I am finding it hard to get a good image of the tile to show that it has a creamy base so I cannot comment on how many firings this would have had but I suspect only one overglaze firing.

 

As you can see from the excerpt lustre can be fired anywhere up to 650-900° C / 1202-1652° F depending on the surface it is on. The controlling factor is the softness of the glaze that it applied to at the temperature you are firing to. The softer the glaze becomes the more the lustre will sink in. This is especially so for low earthenware glazes.

 

As I have said in previous posts Duncan products are rarely, if ever, used by the porcelain painters (the main users of Overglaze techniques). They buy products that are are manufactured by the suppliers and not just repackaged and rebranded as in the case of Duncan overglaze products. I have also never heard of lustres being described as Lustre Overglaze.

 

Regarding Duncan's instructions that you supplied here are my thoughts.

 

1. Any glaze or surface is overglaze compatible. (I don't understand the need for this statement)

2. The firing temperature is suspect. Maybe it is a typo and it is meant to be cone 016. I don't know whether they are offering a normal lustre because lustres starts to burn off after 900.C and they state to fire to 1000.C I would normally recommend firing a cone 6 glaze to 760-780.C however I have refired them successfully to 810.C In your situation where you will need extra mechanical strength I would suggest you run a test and see how the cone 6 glaze interacts with the MOP at 900.C. It is a chore but you won't know until you try as each glaze behaves differently.

 

The MOP that I use is a Fay Good product and can be purchased in the USA from China Painting today. Here is a direct link http://tinyurl.com/mg3ml75.

 

#Ceramics Monthly January 2013 contains a techno file on Lustres

#Pottery Making Illustrated May-June 2013 has an article on how to use lustres.

 

Johanna DeMaine

[LauraAnna]

Sorry – here’s a closer shot of the tile http://www.houzz.com...throom-portland It’s a creamy oyster effect. I know I can’t recreate this - I’m just very curious about what others think may achieve this finish since it is so intriguing. Also this only works well if displayed in an area with ample light or else the effect is lost or muted.

 

I’m glad to learn about the temporary nature of Lustres in regular contact –thank you for that warning. These will be used sparingly as accents, and I’m ok if the finish eventually wears off. That’s when I pull out my handy drummel tool, pop them out, and replace with new ones

I’m new to glaze technicals so with regard to Overglaze vs Lustre I was just recycling phrases I saw elsewhere, either on this site or other supply sites. Duncan site says “Mother of Pearl is a luster, an overglazeâ€. But it seems I should not trust their wording. Would it be more accurate to say that Lustre is a sub-category of Overglazes?

 

Thank you for the referral to your more professional Lustre product. Currently the website says these products are unavailable, but perhaps it is because I am not registered.

 

Very interesting about the glaze/lustre bonding conditions you describe and “softness†of the base glaze. When you say “sink in†– is that a good thing or bad thing? Sink in, as in proper cohesion and optimal iridescent effect (in the case of Mother of Pearl), or sink in, as in the overall effect becomes muted? Granted, there is no bad/good in art - it's all perception, but in my case, I want the full monty! So "good" in this case is full iridescence.

 

I will read the articles you suggested. I have some immediate questions, but they may be answered there. Ultimately, I will just have to test, as you suggested. But as many other users here have expressed, research helps reduce erroneous and wasteful purchases.

 

Your work is stunning by the way – just brilliantly stunning!!