athlon Posted December 18, 2011 Posted December 18, 2011 Hi, was going to try to make some cut stars by wetting some of my chrys #8 mix and flatten it out inside a frame I made. I started by wetting with alcohol but didn't get the right consistency and then remembered that dextrin, which I use as a binder, isn't activated by alcohol so I started to add water to the mix, drop by drop, but all of a sudden the mix got into a state of non-newtonian fluid. Hard when pushed but fluid when letting to rest and not very workable. What went wrong?
nater Posted December 18, 2011 Posted December 18, 2011 (edited) That has been my experience when wetting dextin bound comps with high amounts of charcoal. Way too dry, then add one more drop of water and you end up with goo. I ended up spreading it out to dry, granulating through a screen and trying again. Edited December 18, 2011 by nater
dagabu Posted December 18, 2011 Posted December 18, 2011 Hi, was going to try to make some cut stars by wetting some of my chrys #8 mix and flatten it out inside a frame I made. I started by wetting with alcohol but didn't get the right consistency and then remembered that dextrin, which I use as a binder, isn't activated by alcohol so I started to add water to the mix, drop by drop, but all of a sudden the mix got into a state of non-newtonian fluid. Hard when pushed but fluid when letting to rest and not very workable. What went wrong? SGRS is the only way I have found to bind them with no trouble. I don't know why that is but it sure has worked well for me. Oh, I really hate SGRS but with high charcoal content stars, it works wonders. -dag
dan999ification Posted December 18, 2011 Posted December 18, 2011 too wet, i either use a syringe and measure the water or put the comp in a baggie and spray and kneed it, use hot water and i dont use alcohol take some 10 or more minutes to get the water in bit by bit and wait another ten to activate the dextrin before you cut the stars.dry it mill it start again. dan.
dagabu Posted December 19, 2011 Posted December 19, 2011 Why do you hate SGRS? Good question, I really don't know why but I just get this feeling of disdain when I think about using it. Strange huh? -dag
Mumbles Posted December 19, 2011 Posted December 19, 2011 I've never had a problem wetting stars, even high charcoal ones, with dextrin. It sounds to me most of everyone's problems are impatience. Adding additional water before the part that has already been added gets a chance to fully penetrate or activate the dextrin. High charcoal poses additional problems. It seems like the water soaks into the charcoal, and then gets released a little bit later. It will see drier than it really is, or will end up being. I usually start by adding around 20% water to a composition and mix it in well. I press it into a solid mass at the bottom of the bucket or container I'm using and let it sit for probably 30 min at least. More time can't hurt. Also, I really don't know what effect the alcohol would have. You never mentioned how much you added. If it was more than 10% of the comp in weight you could have some problems most people don't encounter.
dagabu Posted December 19, 2011 Posted December 19, 2011 I've never had a problem wetting stars, even high charcoal ones, with dextrin. It sounds to me most of everyone's problems are impatience. Adding additional water before the part that has already been added gets a chance to fully penetrate or activate the dextrin. High charcoal poses additional problems. It seems like the water soaks into the charcoal, and then gets released a little bit later. It will see drier than it really is, or will end up being. I usually start by adding around 20% water to a composition and mix it in well. I press it into a solid mass at the bottom of the bucket or container I'm using and let it sit for probably 30 min at least. More time can't hurt. Also, I really don't know what effect the alcohol would have. You never mentioned how much you added. If it was more than 10% of the comp in weight you could have some problems most people don't encounter. Even with a 30 minute dwell time on my willow stars, the comp still went from too dry to overly wet so I use SGRS now and it seems to allows for binding across a wider range. -dag
pyrojig Posted December 19, 2011 Posted December 19, 2011 (edited) Even with a 30 minute dwell time on my willow stars, the comp still went from too dry to overly wet so I use SGRS now and it seems to allows for binding across a wider range. -dag That is a interesting way to put it ... SGRS having a wider range for binding despite wetness in high % charcoal stars . Edited December 19, 2011 by pyrojig
dagabu Posted December 19, 2011 Posted December 19, 2011 That is a interesting way to put it ... SGRS having a wider range for binding despite wetness in high % charcoal stars . Mind you, this is just my opinion and is likely that I am missing something that a pro would would quickly point out that I am doing wrong in my methodology. -dag
pyrojig Posted December 20, 2011 Posted December 20, 2011 Mind you, this is just my opinion and is likely that I am missing something that a pro would would quickly point out that I am doing wrong in my methodology. -dag I believe that Shimizu was one who claimed the use of SGRS in high charcoal comps. as a superior binder. Ill have to check again... I believe there is a real truth to this as well.
Timm Posted December 22, 2011 Posted December 22, 2011 Good stuff to know, will have to throw some SGRS onto my next order. Have had some high charcoal stars coming out pretty soft lately.. though it could have been due to my use of the then newly-discovered spruce charcoal, is extremely light and voluminous. In the meantime, suppose I'll just add a bit more binder and pump them out damper than usual.. Being high in charcoal, they will dry out eventually, right? Or is it the high-charcoal stars that have the tendency to be driven-in?
Potassiumchlorate Posted December 22, 2011 Posted December 22, 2011 I still haven't found out the right way to handle SGRS myself. My TT stars didn't adhere very well, so I burned them on the ground.
dan999ification Posted December 23, 2011 Posted December 23, 2011 high charcoal and high nitrate waterbound stars and comps are what suffer from driving in if you mistreat them, i dont find a problem if they are dried properly, over wet and they take two weeks to dry and will crush easily in the first week and be lighter than properly made ones due to the pores the water left behind.yes i would pump with more water and slightly more binder if you have consolidating issues. dan.
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