When I have had conversations with plasterers in the past, this is how it normally goes. (It appears to be similar to our current discussion).
The plaster person tells me that aggressive water just has to be involved with spotting.
I follow up that comment by mentioning that the results of the Cal Poly studies indicated just the opposite. That spotting occurred in some balanced pools and did not in some aggressive water pools. Therefore, workmanship must be involved with spotting.
And that calcium hydroxide is being dissolved from the plaster in the compromised areas.
And that calcium hydroxide is soluble, meaning that non-aggressive water can dissolve it.
That aggressive water can attack compromised plaster areas and spots much faster than balanced water, and thereby cause spotting to occur faster. And that it will take a little longer for balanced water to expose those compromised areas and spots and turn them white.
That four cement laboratories have determined that poor troweling workmanship leads to compromised plaster surfaces that can be affected by non-aggressive pool water.
That plasterers do not have any study or science that provides some substantive information that supports their theory regarding aggressive water causing spotting, or even the other common plaster defects. And they have not provided the type, kind, or degree of aggressive water is required to spot a pool. Would you have some input on this?
After the phase one study, the Cal Poly professors wrote and presented a report to the ICMA indicating that they did/could not prove that spotting was caused by aggressive water. Also, so did David Rothstein (a petrographer that you reference previously). In other words, the NPC leaders misrepresented to the industry that they proved that aggressive water causes spotting.
So, what do these plaster leaders respond with? They say, let’s forget about what happened in the past and do some more test pools. (No wonder they want to ignore what has been learned.) It is simply a diversion and delay tactic.
After those comments, I ask the following question. How does aggressive water also cause gray mottling discoloration, spalling, and calcium nodules? How can it cause all four issues but not always in the same (supposedly) aggressive water pool? And why don't acid washes spot pools and cause these other issues too? That is when they close-down the discussion. In other words, they are misrepresenting what causes those defects too.) What is your position on these other plaster problems? Is is the same as the NPC or not?
If you will respond to the above, we can then discuss our onBalance test pools. I will also invite you to propose a detailed protocol; water parameters, LSI, troweling techniques, w/c ratio, mix ratios, etc.
