Ben Davis Posted May 28, 2021 Report Share Posted May 28, 2021 Hi, i’m looking for some advise / guidance on using water transfer decals. I’ve done alot of tests with mixed results with blistering. I have been making tiles using terracotta clay + white slip fired to 04, with a clear glaze fired to 06. The decals i have used a rubber squeegey, and paper towel or cloth to eliminate air pockets (they all look very smooth) and excess water. The latest firing was as follows: seg 1: 50f per hour. 200f. Hold 2 hrs vented (lid ajar, peep holes open) seg 2: 200f per hour. 800f. Hold 15 mn vented seg 3: 250f per hour. 1200f seg 4: 275f per hour. 1526f hold 20 mn here are some of the results from different highs in the kiln any help would be very gratefully received. cheers, Ben Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted May 28, 2021 Report Share Posted May 28, 2021 How long are you leaving them to dry before you fire them? Link to comment Share on other sites More sharing options...
Ben Davis Posted May 28, 2021 Author Report Share Posted May 28, 2021 The lower right tile was about 24 hrs. The other tiles about a week. Link to comment Share on other sites More sharing options...
Min Posted May 28, 2021 Report Share Posted May 28, 2021 6 hours ago, Ben Davis said: seg 4: 275f per hour. 1526f hold 20 mn This seems like it could be too hot. Have you had the same problem firing lower? I noticed your glaze is quite crazed, is this an issue for you? Welcome to the forum. (nice to see someone from Wales, my dad and sister were born in Illanelli) Link to comment Share on other sites More sharing options...
Bill Kielb Posted May 28, 2021 Report Share Posted May 28, 2021 The glaze looks very crazed on all samples and the transfers on the right appear as if they separated around a contaminant such as silicone or oils. Were these cleaned and degreased thoroughly with a solvent before application? Link to comment Share on other sites More sharing options...
Mark C. Posted May 28, 2021 Report Share Posted May 28, 2021 I agree that seems hot for decals-usually they are at cone 017 or 018 Now for the bubbles -use a plastic credit card or and work from the center out in all directions or your small rubber squeegey paper towels are not the right tool. If they have bubbles add water and try again And as Bill says make sure they are clean. The crazing if its on the tile before adding decals can make for a non smooth surface and will make adding decals very hard as they need smooth glossy surface to work. air bubbles can be seen when dry (use a magnifier) so do not fire them until the bubbles are gone Link to comment Share on other sites More sharing options...
Ben Davis Posted May 28, 2021 Author Report Share Posted May 28, 2021 The glaze firing was to 06 (mini bar) with the kiln sitter, and the glazed tiles do have micro cracks in the glaze. Would cracks in the glaze effect the decals? I have recently purchased the kiln controller to get more accurate firings, which is what i have used to fire the decals. These tests were distributed on all the shelves (5) in the kiln, separated by 2" shelf props. It doesn't seem to make any difference as to which shelf they were on. I cleaned the tiles with surgical spirit (which contains castor oil and methysalicylate) which i saw recommended somewhere. I have also used just water to clean the tiles, and that doesn't seem to make any difference. Link to comment Share on other sites More sharing options...
Ben Davis Posted May 28, 2021 Author Report Share Posted May 28, 2021 The company who print the decals recommend 820c - 840c (1508f - 1544f) at 250c - 300c (482f - 572f) per hour with a 20 mn soak. After doing quite a bit of research it seemed to me the best approach is to have a long steady initial ramp to just below 100c (212f) to eliminate all the moisture. The timings i've used are from a Decals4Artist recommendation. 017 / 018 is around the 720c / 1330f mark. Looks like i'm firing 100c / 212f above that. Would that cause gases in the glaze to be released ? (i've read that somewhere ??) I'm a relative new comer to the world of ceramics, it's a lot of chemistry ! ( i am experiencing both fascination and frustration ) Link to comment Share on other sites More sharing options...
Bill Kielb Posted May 28, 2021 Report Share Posted May 28, 2021 53 minutes ago, Ben Davis said: cleaned the tiles with surgical spirit (which contains castor oil and methysalicylate) which i saw recommended somewhere. I have also used just water to clean the tiles, and that doesn't seem to make any difference. I am not a decal expert but am surprised at any reference to oil. My thought would be denatured alcohol or similar. I ask because the very round dots often indicate contamination with oil based products or oil residue. The glaze crazing simply means the fit with the claybody is not compatible. Likely not good for your decal application and finished piece as well but unlikely to cause the dots. Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted May 28, 2021 Report Share Posted May 28, 2021 Yeah, don’t clean with anything with oil in it. Rubbing alcohol is what you want. Or dish detergent that’s been well rinsed and air dried. Link to comment Share on other sites More sharing options...
Bill Kielb Posted May 28, 2021 Report Share Posted May 28, 2021 21 minutes ago, Ben Davis said: The company who print the decals recommend 820c - 840c (1508f - 1544f) at 250c - 300c (482f - 572f) per hour with a 20 mn soak. After doing quite a bit of research it seemed to me the best approach is to have a long steady initial ramp to just below 100c (212f) to eliminate all the moisture. The timings i've used are from a Decals4Artist recommendation. This is very similar to a China paint application. The dry out segment is usually just a reasonable amount of time below 212f followed by a pretty fast firing temperature to the point of softening the glaze for good adhesion. 482f - 572f per hour is really pretty fast so they really are not trying to go slow by any means. As far as the top temperature I think it would be considered high for China paint but if that is what is needed for their product to melt. I would double check their required top temperature to be sure. Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted May 28, 2021 Report Share Posted May 28, 2021 Ultimately your best resource for firing information will be the company that makes the decal supplies your using, or the decals, if you’re having them made. It’ll depend on the inks they’re printed with, and those do vary. Link to comment Share on other sites More sharing options...
PeterH Posted May 28, 2021 Report Share Posted May 28, 2021 ... two countries separated by a common language. Various posters have advised "rubbing alcohol" and "denatured alcohol" instead of "surgical spirit"., but UK surgical spirit can be correctly described by both those names. While obviously containing additives that probably make it unsuitable for pre-decal cleaning. Are methylated spirits and isopropyl alcohol acceptable UK substitutes? (Both available on www.ebay.co.uk and elsewhere.) Link to comment Share on other sites More sharing options...
Bill Kielb Posted May 28, 2021 Report Share Posted May 28, 2021 46 minutes ago, PeterH said: Are methylated spirits and isopropyl alcohol My vote is isopropyl or methyl for cleaning / degreasing followed by a clean water rinse and dry .......unless at the end of a long hard day then Ethyl alcohol to drowned my sorrows . Link to comment Share on other sites More sharing options...
Roberta12 Posted May 28, 2021 Report Share Posted May 28, 2021 I use isopropyl. The decal site @Ben Davis mentioned says to use a mix of rubbing alcohol and white vinegar. Link to comment Share on other sites More sharing options...
Mark C. Posted May 28, 2021 Report Share Posted May 28, 2021 The part about crazing is some is below the surface (smooth surface) and some is on top of surface (rough surface) . Only you can telll what yours is . If its smooth than teh decal will float on very well and smooth out fine-if the cracks are on the surface than I would not do decals on that surface. In terms of Temps-whatever the company says fireto their recomendations as they know what those colorants need to fuze well. I was specking in general decal terms which for me was cone 017 when I did lots of decal work in the 70s Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted May 28, 2021 Report Share Posted May 28, 2021 rubbing alcohol is Isopropyl alcohol. It comes in varying strengths, and any will work. Link to comment Share on other sites More sharing options...
Min Posted May 28, 2021 Report Share Posted May 28, 2021 Firing the decals to the recommended temperature (1575-1650F) on an 06 glaze might mean the glaze is melting too much by the time the decal is fused on. If possible could you fire a test decal onto something that has been fired to mid or high range and see what happens? Link to comment Share on other sites More sharing options...
Babs Posted May 29, 2021 Report Share Posted May 29, 2021 12 hours ago, Bill Kielb said: My vote is isopropyl or methyl for cleaning / degreasing followed by a clean water rinse and dry .......unless at the end of a long hard day then Ethyl alcohol to drowned my sorrows . You wont see faults either after a while! Link to comment Share on other sites More sharing options...
Ben Davis Posted May 31, 2021 Author Report Share Posted May 31, 2021 Many thanks for all your thoughts and advise, lots to think about, time for some more tests (and ethyl alcohol) Link to comment Share on other sites More sharing options...
Ben Davis Posted June 27, 2021 Author Report Share Posted June 27, 2021 A quick report back on the decal tests.... I successfully fired some decals on commercially made bathroom tiles, cleaned with water and a little washing up liquid, rinsed, and decals squegeed with a rubber kidney squeegee, dried for 24 hours and slowly fired to 820 centigrade (1508F). All good. So it looks like the blistering issue is in my own made terracotta tiles (fired to 04), with clear glaze (fired to 06). Too soft ?? Has anyone got any thoughts on this, or alternative glaze firing suggestions ? Link to comment Share on other sites More sharing options...
Bill Kielb Posted June 27, 2021 Report Share Posted June 27, 2021 27 minutes ago, Ben Davis said: Has anyone got any thoughts on this, or alternative glaze firing suggestions ? So just curious, were the dots the result of using an oil based cleaner or not? And if I might add, the glaze crazing was a sign of a significant difference in the fired coefficient of expansion of the clay and glaze, is the crazing intentional? Perhaps a look that you are trying to achieve with that clear glaze? I did not notice any blisters in your original firing but that could be the pictures. We’re the round dots raised blisters? it almost seems like you may have proved not to use oil based products to wash things off with. Link to comment Share on other sites More sharing options...
Min Posted June 27, 2021 Report Share Posted June 27, 2021 5 hours ago, Ben Davis said: I successfully fired some decals on commercially made bathroom tiles, cleaned with water and a little washing up liquid, rinsed, and decals squegeed with a rubber kidney squeegee, dried for 24 hours and slowly fired to 820 centigrade (1508F). All good. So it looks like the blistering issue is in my own made terracotta tiles (fired to 04), with clear glaze (fired to 06). Too soft ?? I don't think it's been determined if the glaze is softening too much at that temp, my hunch is it is. Since we don't have any info about the commercial tiles we can't ascertain that. Any chance you also fired one of your tiles / glaze with the same cleaning procedure? Would be good to rule in or out the cleaning methodology having an effect. One variable at a time. Link to comment Share on other sites More sharing options...
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