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bijoy

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  1. Thank you @Bill Kielb. But my chalk is for marking cloth. It should be smooth like soap. The only problem is the dark spots. I kept it on 600°C for 30 min today and please see the result below (..
  2. @Min @Bill Kielb @Callie Beller Diesel @Russ Ball clay and bentonite are preferable. How about sodium silicate and 5 % bentonite as inorganic binder with ball clay for better strength?considering the shelf life of inorganic binder. Or can i use 50:50 Ball clay & bentonite or 100% bentonite for getting more strength with only 400°C? Because beyond 400°C organics are getting oxidized and creating dark spots which is highly undesirable. Or can i use hydrogen peroxide to oxidize the organics without making dark spots showed in the picture?
  3. @Russ how about sodium silicate and 5 % bentonite as inorganic binder?considering the shelf life of inorganic binder.
  4. @Bill Kielb Thank you for your suggestion). Can you please tell me how i can increase the ball clay green strength. As ball clay provide the best marking quality on my uses and plaster of paris is not quite smooth at marking.
  5. @Callie Beller Diesel i am making marking chalk. Which will be able to mark easily but will not break easily. Any kind of suggestion is very welcome about this).
  6. It is not matter whether the organics stays or not. I just don't want the black spots. I tried to 600°C for 40 min according to your suggestion. But they are still there (. And also supplying co2 didn't helped me today. They are still appearing from 400°C to 600°C (. Can you please tell me why?
  7. It will used for marking purposes. So if i increase temperature higher then it is loosing its efficient marking capabilities.
  8. Thank you kielb. I am planning to supply co2 gas on the oven when temperature is above 200°C to 550°c prevent burning of the organics. What do you think? Will it work?
  9. Thank you for the reply. Yes. I just want to remove the combined water. By not making it very hard. But facing problem with the black spots. Do you have any suggestion how i can solve this problem?
  10. Thank you for the reply. Is there any alternative to remove them(Organics) without crossing 600°C? Because i don't want my product to be very hard.
  11. After firing at 550°C for 20 min the 100% ball clay surface of the product some black spots of diffrent size and shape (2-15mm). Can anyone please tell me why it is happening.
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