Plaster looking blotchy in spots after our replaster, normal curing or a problem

Started by Marlene Foster · · 3 replies
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#1
We had the pool replastered back in the spring and overall it looks beautiful, but there are a few patches, mostly in the deep end, that look lighter and almost mottled compared to the rest. Gene thinks it is just normal curing and will even out, I am not so sure. Brushed it twice a day like the plasterer told us to for those first couple weeks, kept the water balanced best I could with no test strips back then, just the liquid kit. Chemistry has been steady since, pH and alkalinity right where they should be. Anybody had this happen and had it fade on its own, or does this mean we need to get the plaster company back out to take a look. Not in any rush to panic, just want to know if this is something that works itself out over the first year or if I am ignoring a real problem.

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#2
We had mottling after our replaster too, not quite the same spot but also deep end leaning, and it took the better part of that first summer to really even out. What I remember most is it wasn't uniform fading, some patches lightened fast in the first month and others seemed to just sit there looking blotchy until maybe August, so if Gene's pool is only a few months in I wouldn't call the case closed yet either way.

The detail that stands out in your post is "no test strips back then, just the liquid kit" during those first couple weeks. That's actually the more reliable tool, strips are notoriously loose on readings especially for pH, so I wouldn't second guess yourself there. Mottling in new plaster is usually tied to uneven hydration during the cure, which can come from brushing inconsistency, water temp differences in the deep end, or even how the plaster was troweled that day, not usually something you caused after the fact with your water balance. Since your pH and alkalinity have been steady since, I'd give it through next summer before calling the plasterer back out. If it's still sharply mottled a year out, that's worth a site visit, but at a few months this is still squarely in normal curing territory in my experience.
#3
I'm above ground so no plaster to speak of, buddy, but Alan's point about the deep end and uneven hydration tracks with what my brother in law went through on his gunite pool, his plasterer actually came out around the one year mark and said the same thing, give it a full seasonal cycle before panicking. One thing Alan didn't mention though, ask Gene to check if the mottled spots are also rougher to the touch, not just lighter colored, cause that combo can mean the plaster hardened differently in those areas and water chemistry alone won't fix it even with another year of patience. Smooth but light, probably just cosmetic curing. Rough and light together, that's when I'd get the company out sooner rather than later.
#4
No plaster here, vinyl liner for 25 seasons so I can't speak to curing, but Sam's point about rough versus smooth is the kind of detail that would've gone straight in my binder if I had plaster. I only bring it up because that's the exact distinction I make with liner wear, a dull patch I don't worry about, a rough patch means something's breaking down underneath and it's not cosmetic. Sounds like the same logic carries over even though the material's different.