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<TITLE>Re: [Greenbuilding] Redoing all floors</TITLE>
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<FONT FACE="Arial"><SPAN STYLE='font-size:12.0px'>Non-acid stains like soy stains or polymer stains only sit on the surface and in some of the macro-pores of the concrete. Acid stain works by chemically reacting with the free lime in the concrete and the salts in the stain, to physically alter the chemistry of the concrete, thus changing the color. The white you see could be a white base stain, or, it could be that the concrete was never acid etched before using the sealer. Acid etching removes the “cream” off the surface of the concrete. This is the fine white or grey powder that will eventually dust off the surface. Without removing the cream, any coating or topical stain will eventually peel off the surface, since its only sticking to dust. <BR>
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Grinding and shot blasting are two different ways to achieve the same end result. It its a large area, shot blasting will be more cost effective and will require less prep before the next coating is applied.<BR>
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Andrew Pace<BR>
Green Design Center® <BR>
Waukesha, WI<BR>
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On 7/27/11 5:05 PM, "Ktot (g)" <ktottotc@gmail.com> wrote:<BR>
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</SPAN></FONT><BLOCKQUOTE><FONT FACE="Arial"><SPAN STYLE='font-size:12.0px'>I have been told water-based stain--which was used to get the mottled creative pattern that was intended (without white blooms)--does not sink into the concrete like acid-stain does. Either way, where the stain and sealer have pulled up, there's plain white. It's chalky. Numerous concrete contractors had no idea what that was, telling me my contractor must have done a white layer of stain first, which I knew was not the case. One finally pointed out it's calcium carbonate that chemically reacted to something (the diesel/propane fuel? the exterior stain that was used indoors [as I later found out]?) That makes sense to me as one gets white on the finger when rubbing those areas. The white areas are all white--the stain has completely lifted up. So it does not seem to have gone down into the concrete--unless there is more under the calcium carbonate.<BR>
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Also I should have mentioned earlier much of the sealer seems to have disappeared. When put down it was very shiny (as it was supposed to remain) but now in many areas there appears to be little or no sealer (this is from work done two months ago), and one contractor commented the sealer is soft (vs. it supposedly the hardest, most durable there is per my contractor who clearly misled me in numerous ways).<BR>
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Per the sealer tech rep, the sealer does need to be removed whether I go with concrete again or with tile. He seems to lean towards grinding to remove it. Is that the same as the shot blast you mention?<BR>
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