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Efflorescence problem
JoanA	12-10-2009 11:16:19
Member Posts: 4 Joined: 12-10-2009	Looking for a sealer to stop the snow from coming back. I finished a porch last weekend with skimstone, looked fabulous! Now there is a white snowy section, there were 2 different pours of concrete. This is an old house, not sure when the porch was poured. Needless to say the clients and I are upset with this situation. I haven't applied the nano coat to the skimstone yet, I'm told it probably won't help. Is there a clear penetrating sealer I can apply on top of the skimstone that will prevent or at least minimize the problem. Any ideas?

Lindy A.	12-10-2009 12:41:44
Member Posts: 3368 Joined: 05-11-2009	Is this an on-grade concrete substrate? Could be an excess vapor emission related issue (exceeding 3 lbs per 1000 sq.ft.)? Did you perform a vapor emission test prior to placement of material (this is important when it comes to on-grade or below-grade/basement slabs). Does the lay of the land promote adequate run off away from the perimeter of the slab (concrete is like a porous hard sponge; ergo, it can wick moisture in). Skimcoat of what? A custom formulated/polymer modified decorative concrete overlayment ... or some generic cementitious material from a box store? Was your skimcoat integrally colored? If so, is this the material that you are stating has taken on a random intermingled whitish cast? Nano-coat, of what? Same material as your skimcoat? There are products that could have been applied over the concrete that are formulated to treat/deter rising moisture/vapor; however, this should have been addressed prior to the placement of your skimcoat. If you will answer the above questions, will respond with potential solutions. Lindy A.

JoanA	12-10-2009 13:31:21
Member Posts: 4 Joined: 12-10-2009	I used Skimstone, from Rudd. Skimstone.com, I've used it before and had no problems, until now! No tests were performed! Just power washed, dried, then applied the skimstone, then it rained! Yes it is on grade, it’s the porch and is 2 steps above grade. One section is fine, one section, a different pour is not. It was mush courser than the good side. I figured this was a different pour, however maybe it was crumpling? This house was built in 1930, so I’m not sure how old the concrete is. No one knows. Also the section that is fine has a cover the section that has the efflorescence is exposed to the elements. I did notice that water tends to pool on it though. Yes the skimstone is integrally colored, as I understand it. It’s a multi-layer process, including an expensive Modello. The white powder is even coat all over the section at issue. Nano-coat is the top coat sealer that Rudd sells to seal the skimstone. I guess there's a lot of shoudda's on this project. Yep, live and learn, I never heard of efflorescence until I called Rudd. I’m still waiting for suggestions from them, but thought I would try here too. I have read about sealers on the internet, but I’m not sure about them. Before I try anything I’d like to hear from someone with experience. Really appreciate your response.

Lindy A.	12-10-2009 16:37:21
Member Posts: 3368 Joined: 05-11-2009	Neither covered (good side) or uncovered (side with whitish appearance) sealed yet, right? Both are integrally colored cementatious material, one coat, over prepared concrete (as you described). You put down you skimcoat/Rudd, it then rained on this unsealed integrally colored surface, that you state is not completely level, therefore pooling/ponding of water stood on the effected areas until it evaporated off on its own. How long after you applied this skimcoat did it rain (perhaps before it got a chance to cure out completely, compounded by the ponding water that left an effloresence appearance when it dried)? When whitish deposit area is wet, does the color come back to that of the rest of the surface. Have you tried cleaning it using a neutral PH balanced detergent, scrubbing with nylon bristle broom, rinsing thoroughly, then allowing it to dry completely, being sure to soak/mop up areas where water is ponding? If not, do so ... does it return to the same whitish appearance after doing so? It could be that the rougher/older concrete substrate that has the problem did not have sufficient time for moisture/water to escape that entered deeper down into it during cleaning/prep work (due to its more opened up condition; concrete is like a hard/porous sponge).

JoanA	12-10-2009 17:34:40
Member Posts: 4 Joined: 12-10-2009	It rained about 24 hours after the skimstone application. I waited days before continuing the process, it was fine until the last rain. When I rinse the floor the color look fine, then the white dust appears again. I can try cleaning it, and vacuuming up the water. That could help. I'm also looking into some sealers to add. I'm considering Aldon or CP-1007.

Dr"J"	12-10-2009 18:28:05
My Gallery Member Posts: 330 Joined: --	If this is a polymer topping then the rain could have leached out the excess ploymer in the mix before complete cure could happen. A good scrub as Lindy suggested could help. Also try a test area with a little bit of sealer. Sometimes the sealer will hide this kind of efflorescence if it is not very strong.

tull	12-10-2009 22:16:25
Member Posts: 1 Joined: 11-25-2009	didn't say what part of the country you are from. for some reason the northwest is worse for effloresence. This time of year is also bad anywhere for it. Cold rains make it worse. We use white vinegar cut 2;1 with water. scrub and rinse. Good thing is you noticed something was wrong. Just make sure you get it all off before you move on. I would consider 1 more coat incase of discoloration. Make sure you have a few nice days to coat and seal with no rain.

JoanA	12-12-2009 10:36:39
Member Posts: 4 Joined: 12-10-2009	I'm in San Jose CA. It only rains during the winter here, still it's looking ugly. Thanks for all the suggestions, I'm working with the Skimstone manufacturers, hoping we can find an acceptable resolution. Besides grinding down, sealing, then starting over. I'll wait until the rains stop before doing anything. Anyone know how to test for this? Is there a test, would you just apply water and see what happens before starting? Or seal for it, just in case.

crash	12-13-2009 17:38:15
Member Posts: 10 Joined: --	Because you stated the section that was covered was fine, I would lean towards following Dr. "J"s advice and seal an area first. If had to guess, I wouldnt say it was efflorescence but rather the polymer getting wet and settling on the surface. In many tech datas for polymer modified materials this is a common occurance. Wes

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