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viscosity problems

Posted: Wednesday, July 4, 2012 3:47 PM Quote
we are now starting the top coat with ekopoly and we have a problem.the viscosity when we start painting is set to 21seconds with the viscosity cup,so the first coat is ok and we always had problem with the THIRD and fourth coat.
so after having drops (i don't know if it's the good word in english )every time we have found that the viscosity is changing very fast and the mix is becoming more and more liquid!!!
approximatly every 3minutes we loose 1sec (with the viscisity cuo provided with the kit).so even if we start with 23seconds,15 minutes later we have 18seconds!!!
we followed exactly the instructions,but we used demineralised water instead of distilled water.does someone know if this can be the problem?

thank you
Posted: Thursday, July 12, 2012 1:10 AM Quote
Viscosity changes with temp. If you have your resin and catalyst at 75 deg F and your water at 40 deg (kept in refrigerator) and you mix all the components in a 75 deg room then start spraying them in a 95 deg room the viscosity will drop. The hotter it gets the more it drops.

It is normal to have a 3 second drop over a 15 min period as the paint/catalyst mixture continues to slowly thin out while because it will continue to absorb moisture thats in the solution. In very humid conditions it also absorbs water from the air.

If you want thicker paint start off with your resin/catalyst at 60 deg, mix for 3 min, reduce with cold water to about 26 seconds. let sit for 10 min and reduce further with more water IF needed to hit the 21-23 seconds.

We never have had any issues with viscosity, runs, or poor coverage unless the paint was over thinned to begin with.

We used to shoot at about 19 seconds but found that the 23 seconds worked a little better for most painters.

The proper way to use a viscosity cup is to start your timer when the top of the cup breaks the surface of the paint in your mixing container, Hold it about 6" from the paint level in the mixing container, Stop your timer when you see the first break in the stream.

The M50 cup is Dupont's part number for their inexpensive version of the Zahn #2 cup which is an industry standard measurement. A real Zahn #2 cup is about $100

Make sure you get about 15 seconds from the M50 cup with regular tap water. If it's faster than that you're cup is no good.