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Post by tileman2 on Aug 28, 2015 22:46:01 GMT -6
Arnie:
Going to move our conversation about testing the various aspects down to this section. Tonight I took two 9 x 12 tiles and cut them into quarters. Test tile 1 has 5% CU with .25 MNO, and tile 2 has 3% MGO and 1% CU. They had been sitting there for years; so into the brink they go. ( cone 9 original firings)
Each cut into four sections:
Section 1: not subjected to any treatment/s- control piece.
Section 2: 24 hr soak in HCL @ 0.52PH.
Section 3: 24 hr soak in sulfuric acid @ 0.12 PH. (started bubbling soon as it hit the solution- heated to 130F)
Section 4: 24 hr soak in potassium hydroxide @ 13.58 PH. (crystals began to brighten within 30 minutes)
Tomorrow night they will be rinsed/neutralized and fired to 1350F, with a 15 minute hold. Pictures to follow Sunday.
Lets find out if that is true or not. 2 different kinds of acid and one caustic alkali.
Tom
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Post by tileman2 on Aug 29, 2015 22:03:19 GMT -6
Control piece # 1- no alterations made. 5% CU/Red with .25% MNO Cone 9 original firing.  Piece 2: HCL soak 24 hrs. Mix ratio: 1 to 1 Notes: small particles of fired clay left in bucket. (HCL appears to attack clay body)  Piece 3 Sulfuric Acid soak 24 hrs. Mix ratio: 2 water to 1 acid. Began changing color to blue in some areas.  Piece 4 Potassium Hydroxide soak 24 hrs. Mix ratio: 10 to 1 Color changes, outer growth ring turning black/ field brightened.  Pieces now being fired to 1365F with 1 hour hold. Tom |
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Post by tileman2 on Aug 30, 2015 12:02:18 GMT -6
Striking results: 1365F - 1 hour hold. 1-control piece 2 HCL 3 Sulfuric 4. Potassium Hydroxide  Notes: 2HCL attacked crystal formation/partially destroyed. 3.Sulfuric altered crystal structure and added some blue to field. 4> Potassium kept crystals in tact with highlights, added deep blue to field. 1365F caused some matting- 1325F on next test. The above test piece was 5% Cu/Red- the test below is 3% MNO with 1% Cu-black. Testing how etching effects other colorants. 1. Control piece. 2. HCL 3. sulfuric 4. Potassium Hydroxide. 1365F- 1 hour.  Notes: on pieces with high % of colorants/ low CU amounts HCL performed better. In this case sulfuric attacked crystal formation. Potassium Hydroxide did brighten the field and added a slight mauve appearance to crystals - camera did not pick up this highlight. Personal observation: Sulfuric and Potassium are much more effective on pieces with high % of CU. HCL may be more effective on pieces with high % of colorants and low % CU. The intensity of the solution plays a minor role; full strength seems to be corrosive only. The next test will be at 1300-1325F- 1365F mildly etched the glass/glaze. Tom |
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Post by tileman2 on Sept 1, 2015 17:26:09 GMT -6
Tile 1: 2% black CU. Tile 2: 2% Cu-carb w .50 MNO 72 hour soak in Potassium Hydroxide 13.84 PH [Edited to 72 hr soak time.]  The crystals on tile 1 from the 1-4 o'clock position have a tanish color with a green/grey area behind them. Note the celery green to medium green in tile 2 along with green in the crystals.  [Photo replaced] Notice the deep blue/Lt green color in the field in tile 1: the brown crystals are likewise taking on a blue cast. Tile 2 has lightened considerably in tone and the crystals have taken on a silver/white color- losing a fair amount of green tint. Both will be strike fired at 1340F for 1.5 hour. EDIT [ photo 2 was replaced because of poor quality.] Tom |
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Post by tileman2 on Sept 3, 2015 22:08:22 GMT -6
The final results from high alkalinity etching and strike firing. PH 13.84 from potassium hydroxide; soak 72 hours- strike fire @ 1340F [766C] for 1.5 hours. The effects were so dramatic I decided to repost the test pieces in their original condition before any processing. Then after 72 hour soak and strike firing at 1340 for 90 minutes:  The 2% black CU completely changed crystal color to a roman bronze. The highlights at the top of the tile reflects the color the best. The field went from dark green to dark and light teal. Tile 2 the field changed colors completely; with the crystals ranging from silver, light green and brown. In addition, no matting occurred, nor were any of the original crystal shaped altered or damaged. The glaze also retained its original high gloss appearance. Pending upon the desired effects: each 24 hour period of soak changes the overall effect. Tom Tile Art Studio |
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Post by Arnie Benton on Sept 4, 2015 11:07:59 GMT -6
It sure looks like alkali can have dramatic effects as well as acid. Differences between 1 and 2 are the Mn addition to 2 and less Cu in 2.
I just got some TSP to try -
Arnie
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Kuba
Full Member
SztukKilka in Old Formu
Posts: 111
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Post by Kuba on Sept 4, 2015 11:33:24 GMT -6
Tom, very interesting results you get. Personally I love to use HCL. I have pots that I fired in oxidation, thrown into acid, strike them, hcl again and reduce after that.  But this is just for fun... This one is an example of oxidation firing/HCL/strike:  Possibilities can change dramatically with using such technique  |
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Post by tileman2 on Sept 4, 2015 17:00:34 GMT -6
Kuba: Very nice finish product. I cannot see the crystals very well; but did the HCL soak alter the original crystal formations? The one thing I have noticed so far: etching softens high levels of colorants from deep to medium or pastel. When used on low percentages of colorants; it can change colors all together. Kuba: what was your total soak time, strike temp, and hold times? Trying to build a database for all to use.
Arnie: Several notes of interest. 1; The higher the concentration; the shorter the soak time. 2. The longer the soak time, the more dramatic the effects. So far I have used it on Cu, Mno, and Mgo: and all three have reacted to it. I currently have Co soaking. and have some rare earths I am going to try. 3. Do a complete rinse in vinegar or some other mild acid to neutralize the alkalinity: leaves a white scum if you do not.
Also running some tests with sulfuric acid; I liked how it highlighted the crystal nucleus. HCL seems a bit too corrosive on CU; it destroyed some of the crystals in the early test pieces.Still along ways off from final results; but it seems HCL works on some colorants, sulfuric on others: but alkalinity seems the safest for all.
Tom
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Post by jfox on Sept 4, 2015 20:47:48 GMT -6
Love those tests thanks Tom
had a pretty good week but now im stuck in La cause my sister is in the hospital and she was taking care of my mom. life gets to complicated
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Post by tileman2 on Sept 4, 2015 23:04:34 GMT -6
Jim:
Glad you had a good sales week, but sorry to hear about your sister. Hope for a quick recovery for all.
Got a few ideas about reduction; when you get back on schedule will go over some research. Might be some alternatives to reduction that have not been tried yet. Sounds right on paper, but you know how that goes. The one thing I do like about alkaline based soaks and re-fires- does not alter crystal structures.
Tom
Arnie- would also suggest trying a 1325F peak- alkaline seems more reactive to heat that acids.
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Post by tileman2 on Sept 5, 2015 18:19:58 GMT -6
 TSP 11.6 PH > sodium silicate TSP 90 13.45 PH > sodium silicate Pot. Hydroxide 13.85PH More info for those wanting to explore alkaline based etching. >> Arnie: soaked 2% CO in sulfuric for 48 hrs - 0% net change in color or crystals. Tom |
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Post by Arnie Benton on Sept 9, 2015 9:37:23 GMT -6
Here are my first tests, using the phosphate free TSP -
This first piece has been fired five (5) times - it has Ru4 Cu2 Ti3
first firing -
2 - struck  3 - post fire reduced -  4 - etched in acid-  5 - Alkaline etched  The Acid etching in 4 pretty much returned the piece to it's appearance before reduction, but with some Cu removed - then the alkaline reduction produced something very different. And the second piece - Fe2 Co.3 Ti4 first - crystalline firing -  2 - post fire reduced  3 - Alkaline etched  Again, the alkaline reduction changed the crystal color dramatically. My first guess is that the alkaline reduction is changing the color of the iron - in the Ru in piece #1 and in higher concentration in #2. Lots more to do to even start to make hypotheses about this - Arnie Looks like I have to figure out how to decrease the size of the pictures.
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Post by tileman2 on Sept 9, 2015 14:46:04 GMT -6
So Arnie:
Did I get you hooked on alkaline? LOL
Personally I prefer alkaline etching; it is safer first off. Secondly it does not alter crystal structure, which I have seen many times with HCL. Soak periods are the primary factor, then heat, and heat soak time/s. Did you lower your peak temp after alkaline etch? Love the "bronzing" effect it has on the crystals- metallic almost.
1. Noticed the grazing problem has gone; silica/alumina under flat pieces allow them to move.
2. Noticed the alkaline etching actually highlighted your layered glazing technique.
3. Test result: alkalinity had zero effect on Co pieces: 2% CO in pot. hydroxide for 72 hrs - 0% change. To date, alkalinity works on Cu, FE, MNO, MGO, and rare earths- but not CO.
Tom
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Post by Arnie Benton on Sept 11, 2015 10:39:10 GMT -6
It gets a little more complicated - Here's another Ru4 Cu2 piece -  and then reduced -  Next, alkaline etched -  and finally - since I used dishwasher detergent(!) for only about 13 hours to produce #3, I decided to repeat the process to see what more alkaline etching would do - again, in dishwasher detergent for another 12 hours -  Oops - not so good. So it looks like we're looking for something more subtle, having to do with strength of alkali and time - Arnie |
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Post by Arnie Benton on Sept 11, 2015 13:26:24 GMT -6
So, what the h - I decided to acid etch the last piece -  I guess that completes the cycle - Arnie |
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But this is just for fun...
