Monday, July 19, 2010

Why do I have blisters in my sealer?

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Q. -  We've used a solvent base sealer product two seasons now and both times were done in proper weather conditions and both times bubbled (blistered). Could this be because surface of patio is hotter then outside temp (although we applied it one year at 6am and the other time at 8pm) or is it because we're putting it on too thick? This condition is after first or second coat, didn't make a difference.
 
Hello Bill
 
A. -  When solvent base sealers blister during application, it's because the temperature of the surface it is being applied to and/or the air temperature is too hot. Strong hot direct sunlight will also cause it. What happens is the Xylene or whatever solvent the sealer has as a base, tries to flash off too fast and it blows bubbles in the sealer as it exits.
  
   A couple points: Rolling a fresh coat of sealer on should re-liquefy the existing sealer, allowing both coats to settle back out, and effectively remove the bubbles completely. That is if it's done when it's not too hot, otherwise they would just come back. You are correct that the concrete temp was likely hotter than the air temp, especially if it had direct sunlight. Perhaps you should try to seal early in the day, after it has had the night to cool, and preferably in the shade, and in a temperature range of the 70's F, and no higher than the low 80's F if possible. If you are continuing to get bubbles and blisters then you may need to seal during a cooler time of year, or switch over to a water base sealer.
   Finally, if you do start getting blisters during sealing, then you can use leaf blowers to blow across the surface of the sealer after you seal it - yet before it dries, which will pop the blisters and allow the sealer to settle back out, and dry down without them.

Monday, July 12, 2010

Which tape is best for creating a pattern or border?

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Q. -  When doing a  complicated pattern, what type of masking tape do you use?
 
Hello Chris,
 
A. -  The best tape you can use to create a pattern and/or a border on concrete when concrete staining, is actually a packaging tape. The kind that is a clearish looking, with the strings that run through it. You can find the packaging tape that has the strings running through it (clearish - like a plastic type of tape or a heavy duty scotch tape sort of tape - just be sure that it is not a paper tape, and that it does have the strings running through it) at about any packaging store, ups, fedex, etc.

Wednesday, July 7, 2010

Why do I see more red in some areas than others?

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Q. -  I stained with island sand applied using a garden sprayer in a circular motion.  Surface was scrubbed with TSP and rinsed thoroughly before applying.  There are noticeable redder marks in some areas.  I think the overall look is good still, but is there a reason for this?

Hello Sean,
 
A. - The stain works by chemically reacting with the lime, cement, and minerals in the concrete, to change the pores and surface of the concrete to the new and permanent color. When your concrete was originally poured into place, that lime and cement and all the other components were randomly dispersed throughout.
   The stain is simply reacting with what is there and where it is. Of course you can highlight with other colors if you like, but if you're happy with it you may want to just leave it alone.
   Another consideration is that if you seal it, then that will change the color's appearance as well. The solvent base sealer will make it look as it does when saturated wet with water, and the water base sealer will make it look as it does when it is damp with water.