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ceramichetigrini

Strange effect airbrushing my glaze

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Hi,

 

I just took out from my kiln my long worked plate and I had a very bad surprise sad.gif.

As you can see fro the attached photos (before and post firing) all the colors seems de-focussed and it is full of white scratches.

I used a glaze for majolica, as usual. The only change I made was to spray the dish with the white glaze instead of pouring it.

Surely the problem is related with the use of the air-gun but I have no idea why. Any hint or suggestion?

Thanks.

Alessia

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I try again to attach the photos... Maybe I made something wrong.

Hope it works now.

Thanks

Ale

Photos? Not showing up on my computer....

 

 

 

post-16370-135163579297_thumb.jpeg

post-16370-135163606788_thumb.jpeg

post-16370-135163590235_thumb.jpeg

 

 

 

Sorry from your pics I do not see any scratches. Are you sure they are not cooling cracks(craziing) from opening too soon? I do notice the pebbly effect especially in the blue, this could be from uneven glaze build up from a poorly adjusted air brush.

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Hi,

 

the kiln was opened two days after the firing and it was at 23 C so I don't think it is a problem related to the temperature. I'm pretty sure it is due to the airbrush but what I don't know if the glaze was to thick, or just irregular or ...

For scratches I mean the white dots you see especially on the blue, they look like rips in the color.

Thx again.

I try again to attach the photos... Maybe I made something wrong.

Hope it works now.

Thanks

Ale

Photos? Not showing up on my computer....

 

 

 

post-16370-135163579297_thumb.jpeg

post-16370-135163606788_thumb.jpeg

post-16370-135163590235_thumb.jpeg

 

 

 

Sorry from your pics I do not see any scratches. Are you sure they are not cooling cracks(craziing) from opening too soon? I do notice the pebbly effect especially in the blue, this could be from uneven glaze build up from a poorly adjusted air brush.

 

 

 

 

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What did you use for the base and what did you use for the majolica airbrush? Looks like you may have had frit in the blue design color that allowed it to move and reveal the base glaze (white?) Majolica requires a non-moving glaze for the base and top coat. Did you meet those requirements?

 

You airbrushed the base white and hand brushed the design?

 

PS - Gorgeous design! smile.gif

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Hi,

 

the kiln was opened two days after the firing and it was at 23 C so I don't think it is a problem related to the temperature. I'm pretty sure it is due to the airbrush but what I don't know if the glaze was to thick, or just irregular or ...

For scratches I mean the white dots you see especially on the blue, they look like rips in the color.

Thx again.

I try again to attach the photos... Maybe I made something wrong.

Hope it works now.

Thanks

Ale

Photos? Not showing up on my computer....

 

 

 

post-16370-135163579297_thumb.jpeg

post-16370-135163606788_thumb.jpeg

post-16370-135163590235_thumb.jpeg

 

 

 

Sorry from your pics I do not see any scratches. Are you sure they are not cooling cracks(craziing) from opening too soon? I do notice the pebbly effect especially in the blue, this could be from uneven glaze build up from a poorly adjusted air brush.

 

 

 

 

 

 

Ok rips in the color-white dots. Did you bisquefire the underglaze on? If not I am wondering if you got the area wet with the airbrush and that caused that particular underglaze to separate

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Hi,

 

I just decorated the plate which I bought bisquefired.

 

I used a majolica glaze for the bottom (it is an italian one called "SLA274" colorobbia unleaded glaze), which I already used several time. I used the airbrush for this white bottom, after few days I made the design using the technique called "spolvero" and then I decorated it using brushes. The colors I have used are called in Italy CSM which are colors used for decorating the majolica. I used them several times without any problem. The only new step I used was to airbrush the white glaze instead of pouring it, as usual. Of course, was a bad idea! :(

 

Thanks for the comments

Ale

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I also think the majolica was moving. I'm not sure about the thickness, since it was the first time I used the airbrush for the base and I had no feeling about how much I should

spray. I had the suspect the base was too thick but was not sure and I went on with the decoration. Anyway is useful to learn!

 

Ale

I'm with scoobydoozie and bcisketpottery on this. Looks like your majolica is moving. Probably because the majolica base glaze is too thick.

 

Jim

 

 

 

 

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I also think the majolica was moving. I'm not sure about the thickness, since it was the first time I used the airbrush for the base and I had no feeling about how much I should

spray. I had the suspect the base was too thick but was not sure and I went on with the decoration. Anyway is useful to learn!

 

Ale

I'm with scoobydoozie and bcisketpottery on this. Looks like your majolica is moving. Probably because the majolica base glaze is too thick.

 

Jim

 

 

I agree that it looks thick. Majolica doesn't usual move much. Just keep practicing with you airbrush. Try to gauge the thickness of the sprayed with a pin tool and keep track of what thickness work. It goes on fluffier than pouring so allow for that.

Marcia

 

 

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Thanks Marcia I will try again making more attention to the thickness of the glaze. Maybe I will start with more low level decoration, so I will not so desperate at the end ;

Ale

I also think the majolica was moving. I'm not sure about the thickness, since it was the first time I used the airbrush for the base and I had no feeling about how much I should

spray. I had the suspect the base was too thick but was not sure and I went on with the decoration. Anyway is useful to learn!

 

Ale

I'm with scoobydoozie and bcisketpottery on this. Looks like your majolica is moving. Probably because the majolica base glaze is too thick.

 

Jim

 

 

I agree that it looks thick. Majolica doesn't usual move much. Just keep practicing with you airbrush. Try to gauge the thickness of the sprayed with a pin tool and keep track of what thickness work. It goes on fluffier than pouring so allow for that.

Marcia

 

 

 

 

 

 

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Back when I used to spray glazes, I would shoot for the thickness of a dime. I would check it by making a small scratch with a needle tool. You probably don't have a U.S. dime in Sicily, but find something to use as a reference once you establish the proper thickness.

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