I have the Nashville clients’ project finished, with the last two crates shipping in the morning, and the city pool projects’ concrete panel finished as well.
The concrete pool panel turned out to be a major pain unlike any other! and to think, this is a donated sculpture and it was to be a simple matter to cast the concrete into the mold I made. After casting the first one there were two things I didn’t like, one was it had a lot of fair sized air bubble holes on the surface, the other was the acid stain I’ve used so well on many concrete casts absolutely looked all wrong for this bas relief- way too dark.
Ok, so I decided to cast another one and use a different stain, same story there, lots of holes on the surface and the other stain didn’t look right either!
So I cast a third one, this time I decided to nix the stain and go with an integral concrete color, but this one too despite my best concerted efforts also had a lot of holes in the surface! Concrete will always have some no matter what you do, but this went beyond the definition of “some.”
So I re-examined the whole process to see what may have changed, then I figured out there was only one thing I had changed from the usual and that was making use of my large powered concrete mixer to mix up the dry material. I thought about how that worked and realized it was almost certainly fluffing up the sand and Portland cement enough it was putting lots of air into it.
So the 4th try I mixed the concrete up the normal way I have for years- by hand in a rubber tub, and I decided since panel #3 was not quite as red as I was hoping for, and that I had not used the maximum amount of color yet, that I would go ahead and add two bottles of it to the 12 quarts of water for the 150# of concrete to get it a little darker.
The product can be used one bottle to 60# of concrete, I used one per 75# and kept it a little less than the maximum but more than the 1-1/2 bottles I used for #3.
Now that it cured for a couple of days I took the cast out today and it came out good, a small amount of tiny air bubbles as normal/usual and certainly nothing like what I had with #1, 2 and 3. It looks like it will turn out to be a pleasant red terracotta color when it’s fully cured and dry.
So now we know- stay away from any mechanical mixing of even the dry ingredients! I knew to stay away from mixing the wet concrete that way, but it never dawned on me mixing the dry ingredients would cause issues.
Hopefully in a few days I can get a photo of the panel, meanwhile my right middle finger is feeling better, after having been banged a month or so ago and the nail turning black and blue, it was half replaced by the new nail when you guessed it- it was smashed again the other day wrestling the over 100# plaster mold for the pool cast down the stairs, I lost my footing a bit and tipped towards the stone wall and of course that finger was the one that was between the mold and the stone wall and was half scraped along the rough stone and half smashed
So here it was shortly after:
As if that wasn’t enough torture for the week, while casting the concrete I wear rubber gloves, but this time I didn’t notice the left middle glove finger tore open and as I was moving my hands around the rubber tub mixing, the fingernail caught right up against a small bit of hardened concrete and broke a small piece of nail off.
Just lovely, now both middle fingers are messed up for now!
Hopefully next weekend I can get back to the Butterfly child/Mulcaster building model, I’ve not worked on it for a while and need to finish it, but right now the thought of having these two fingers in gritty wet clay is not a good idea.