The last piece I made that cracked was done in the shade and cool. Couldn't have been from too fast evaporation. It was quite detailed so I think possibly just moving the mortar around for too long may have something to do with it. What do you think of that? I remember at your seminar in Seattle you would let a lot of seemingly good product fall to the ground during initial shaping...was that because at such an early stage it was already too far along in the "set curve" to be safe using?
The Original 19 sounds like a good idea, maybe moreso for hot days, no? I trust this won't interfere with the staining process after applying it.
Nathan Giffin Vertical Artisans said:
You can also spray a coat of EZ slick over the surface when your done... Specco.com also known as Original 19 and its the third component of the One Day Wall System.....
This will gelatin the water and keep evaporation at a low...
Guess one thing I would really like clarification on is how long I can move the mortar mix around for. I have an uneasy feeling that the cracking I'm experiencing may have something to do with moving/ reshaping the mortar too long into the cure cycle. Is there a rule of thumb to determine how long is just right, and how long is tooooo long?
Thanks for the info on plasticizers/ reducers and delay set. Are plasticizers and reducers the same thing or different? I do like the idea of a delay set for doing more detailed and time consuming pieces.
Christian Maucieri said:
There are a few things you can do that will help. First if you are indoors or in an area where it is not too warm you can break your initial set by re-mixing after 5-10 minutes. What I mean is add all of your ingredients, mix them together, let them sit 5-10 min and then do some re-mixing. This should help extend the workability of your mix. You can add a splash of water, a tiny bit at a time until it's perfect again but I would only do it once.
Secondly, you can use plastcizers/water reducers and or delay set. You can go to fritzpak.com and find what you need there. Plasticizer 5 is a good place to start, it's a powder that you can add to your mix. Add a teaspoon at a time as a little goes a long way. You will add this to your mix only when you want to reconstitute. There is actually enough water in your mix without adding more, the plasticizer will release the water thats already there back into the mix preserving your strength.
To get a longer working time in hot conditions or when you just want more time so you don't have to rush, you can add a "delay set". Again use maybe a teaspoon to a tablespoon per bag until you see what it can do. If you add too much, it will be a very long day or even two days if the temperature is cool or indoors as you mix will take forever to set up enough for you to do your carving.
I personally like to use Kirtbag as a pre bagged mix. Jeff Kirt has carefully crafted a mix that I find works perfectly for vertical applications and or rock work. The only thing I have ever had to add to Kirtbag was a little delay set on hot days. You should call Jeff (903) 279-7525
Ken, as it happens, everything that cracked on me wasn't yet sealed, but even so I would be very surprised if this was the trouble. Lots of stuff I built never cracked and it wasn't sealed either. And with all the underwater stuff that I am building I am sure that the mix would have to stand up underwater even without sealing, because sealing stuff underwater wouldn't make a whole lot of difference as water will get in anyhow. I am sorry you are having similar problems as I know how frustrating and expensive these screwups are. I have kissed goodbye to 6 or 8 weeks of hard labour. Thought I was the only guy who couldn't get it right every time.
Honestly, I am starting to doubt the product, like maybe it has some serious, inherent limitations to it. The guy at the Trupac Help line said the mortar shouldn't even get wet for minimum 2 weeks after placing it. That doesn't sound right to me. After all, I built an 8 foot high rock about 15 feet long and started wetting it copiously soon as it dried. I let the hose run on it for hours, days on end. It's perfectly solid all through still.
I still think my cracking problem has something to do with continuing to move and shape the product too far into the cure cycle. I'm trying to discover if there is a rule of thumb to determine when the mortar has reached a drying point in the cure cycle and should be left alone or cracking will occur. If I ever find out for certain I will be sure to share the info with you.
ken snyzyk said:
hey steve are you sealing the work at all?I'm having same problem,some jobs are great some all cracked.I'm always using same product can't figure out why.Gonna try sealing the jobs sooner after completing them like the patio guys do.I think the cracking might be weather related,damaging sun not sure but most cracking for me are the jobs in full sun all afternoon.