My white pool plaster turns grey or off white when wet.

[mikes112]

So I'm about to plaster and I'll admit all but really only one sample came out white, the rest are all too grey or off white when wet, but my existing pool plaster is a much brighter white when wet. What exact mix are pool plasterers using? Does it have something to do with the marble dust aggregate "poolmix", or the white portland cement . The popoff that I repaired with the proportions of pool mix that OnBalance has reccomended. In one of my photos you see an all white sample and that was just straight white portland cement type 1 with distilled water. I tried SitkaPros white bonding agent. I tried distilled water. I tried mixing the water with only the white portland cement first because I realized the marble aggregate is absorbing some of the moisture. I really believe now that who ever plastered this pool before me used alot more portland then aggregate. I just finished surface grinding about 750 squarefeet of the 830 square feet of my pool surface, and its a nice white color! And well bonded, but I need to add some plaster. The one that came out white was mixed with about 75%more water then reccomended, and was premixed with the white portland cement before adding the aggregate and used hard tap water which has a small amount of calcium chloride in it be cause I have hard water. It seems the real trick is how to get a thin layer of the white portland to stay at just the top surface to get a white pool. Go figure. And I only used plastic utensils to mix, no metal.
Here it states if theres more water at the surface it will dry lighter. Does concrete dry darker or lighter?

 

[mikes112]

I have found that my problem was the white portland cement I was using was not white. FederalWhite's portland cement and Lehigh's white portland cement were both a slight tint of tan when wet, but when dry they were white. I found FederalWhites type S masonary cement to be significantly whiter. Does anyone know why? Do you do a test of the portland cements as a plasterer before you purchase them?

 

[zea3]

I'm going to ask a couple of people to look at your question and give their opinion. @onBalance @JamesW @jimmythegreek

 

[onBalance]

As cement, and pool plaster hardens, it will become lighter in color. And that does take at least a few months or more. That is one reason why your old plaster is more white now than your new plaster. And yes, when plaster dries out by draining the pool, the plaster becomes very white, and become off white when wet again. Nothing can change that.

You could go with a 1:1 cement/sand aggregate mix (instead of a 1:1.5) to produce a more white finish.
Adding more water also helps to produce a more white result. But I suggest not going more than a .50 water/cement ratio. Otherwise, the plaster quality will be poor and will not last long and will stain easier over time.
Do not add any calcium chloride to the mix as that will result in an off-white color. Do not over trowel as that will also likely darken the finish.

 

[mikes112]

David Ojeda of Fritz Pak corp has stated I should use titanium dioxide as a white colorant. Has anyone used this successfully and know of a not too expensive source? Thank you.

 

[onBalance]

Fritz Pak is a good and reputable company.
Sorry, I have no first hand experience with using titanium dioxide to make white plaster more white.

 

[mikes112]

I only need to do a thin skim coat on the surface and two areas where I had to grind down to the pool shell because there was green algee growing in the cracks. So I tried to get Diamondbrite and SGM's Peal brite marble ready mix, but there both 12 weeks out from all local distributors. Currently I have 4 bags of pool mix marble aggregate I bought last year and 5 bags of white portland and one bag of FederalWhites type S mortar which dries a nice white, but has lime in it which they said is not that stable for underwater use. I am currently purchasing Titanium dioxide to mix in for better color which arrives monday from ebay. WetEdgeNJ has agreed to show me one of his plaster jobs in a couple of weeks. I am seeing a lot of videos of people using white pool plaster, looks like SGM's Diamonbrite. Maybe its also the acrylic fortifier as well in the plaster that makes it look so white? I could try adding that. Something scary but interesting, when I spray SitkaPro's white concrete bonding agent on the plaster it seals it and you can't get the area wet or porous again for bonding but it stays perfectly dry and white, maybe thats what Im seeing. But if thats the case how come were not sealing the plaster surface? Or maybe it wont last. If theres so much negativity about acrylic pool paint then how come no one is complaining about acrylic bonding fortifiers in the mixes? You know for what the plasterers are charging and me doing this myself Im wondering if I should just get all that excess free marble tile I have and just tile the whole thing and it will last forever, but of course marble needs to be sealed as well.