Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison
So what does really happen with the ink's viscosity when it is stroked?
How does that impact our ability to print with it?
More of questions then comment. I understand how heat will affect the viscosity of the ink but does the constant shearing of it reduce the viscosity. In other words if a new pail of ink has a viscosity of 1000 cSt (I don't know the actual just pulling numbers out of my a$$) then you run a job and due to the constant shearing is the viscosity reduced to let say 990 cSt. Then the next job more viscosity is reduced by shearing. If you load a screen with ink, run a job then scrape the ink out and put back in the bucket and mixing it is this reducing the viscosity of the whole bucket? Over time a 5 gallon bucket would go from 1000cSt to maybe 800 cSt, by the time you got to the bottom if would be essential a completely different ink. I know in high pressure hydraulic systems you should avoid using needle valves on the high side due to the nature of the needle actually cutting the oil reducing its viscosity and lubercating properties. Is the same happening shearing the ink across the screen?If the ideal temp for a pallet is 140 and the ink 100 with the transfer of heat between the pallet and screen/ink it is almost impossible to maintane the optimal ink temp? Wouldn't it be better to make the inks to have ideal printing traits at a higher temp like 140? Or better yet a multi viscosity ink that will be optimal at a range of temp and change accordingly.How does the "slickness" of the emulsion effect the viscosity and shearing properties of the inks. If you have an emulsion that creates more drag on the squeegee then another will that affect the viscosity?Sorry to ramble on and maybe none of it matters in the end, have lots more to over think on this topic.
We could have two different inks though, one for cold printing and one for hot.
Alan,Good example of what speed does. Correct me if I am wrong, a faster print will change the amount of downward force over a slower one. The angle will also change if your pressure is enough to bend the blade. I have seen good results over the last few years speeding up my prints.
Quote from: Jon on May 07, 2014, 02:24:33 PMAlan,Good example of what speed does. Correct me if I am wrong, a faster print will change the amount of downward force over a slower one. The angle will also change if your pressure is enough to bend the blade. I have seen good results over the last few years speeding up my prints. Joe has tried his best to explain it to me and there is some great info in the textile printer's bible explaining those dynamics but knowing how those things work enough to explain it here is not something I think I could do. I know the goal is to have zero force being applied to the pallet and we all know that applying less pressure from the squeegee will help to reach that goal and then speed will affect it as well but to what degree I'm not too sure. Blade selection, off contact, ink well, and a bunch of other things are involved as well, or perhaps not just involved but may be more important to the force on the pallet, that stuff is over my head right now.
Some times a little farce is needed to set that ink down.