Hello Folks! My name is Bryan. I am a journeyman Carpenter in Alberta, Canada.
Recently I poured my first concrete countertop. My questions are:
1. I poured concrete with no color and the intention of simply sealing it with a sealer that would provide a “wet” look to the concrete. What is the best product(s) for me to accomplish this? Can I apply this with a brush or rag or roller, or does it have to be sprayed on?
2. With the small “pocks and divots” that remain in the edges and some in the top. What is the best way to fill some of the larger ones? Cement paste mixture?
I appreciate very much any advice that anyone could provide.
Thank You very much.
Bryan Skrypnek
Cochrane, AB, Canada.
Replies
Can't help you with a product to give you the "wet" look, but as for the small voids, simply make a slurry mix and take a thin, plastic blade, (putty-type) and apply a thin coat. Beck
Hey Bryan, just out of curiosity, did you pour in place or off-site? I have recently taken Fu Tong Chengs workshop and am getting ready for my first project....a bit nervous, any suggestions?? Thanks, Beck
Concrete is growing in popularity. I just poured mine last Saturday (cast upside down). Took me a weekend to properly build the melanine mold. I can hardly wait the week to let it cure before unmold it. I read Cheng's book very thoroughly but still made some mistakes.
The good: Be sure to rent a mixer...it is so much easier and only cost be $16 for the 2 hours. I vibrated by clamping the blade of a reciprocating saw to the mold. That worked great.
The bad: I poured half the concrete, then lay in the rebar/remesh, then poured the rest of the concrete; I fear that the vibrating may have settled the rebar to the bottom of my mold....the finished surface. So in hind sight, I would be sure to suspend the rebar with some wire. Be sure to level your mold before the pour; I was 3/8" out of level and it shows. I used a very stiff mixture that was impossible to screed....I will have to see if that was a mistake and if I have a lot of voids or not.
The ugly: Will have to update you after I unmold it.
Richard
San Jose, CA
Hi,
I asked a similar question on the forum last night but my post never showed up. I work as a cabinet maker and carpenter in Nova Scotia, Canada.
I am in the middle of a set of concrete countertops for a customer of mine and have a question about the wax that people are using. These are my first set and the pour went great with very few imperfections. My problem is with the sealing and waxing. I used a beeswax/orange oil blend as a final finish over a penetrating sealer but the customers are not happy with it because if you leave water sitting on it for a while the wax softens and rubs right off. They love the counters though so I just have to solve wax problem. My next try will be some carnuba added in and only enough oil to make it soft enough to apply.
Everything I have read just says to use "paste wax" but I am trying to keep away from anything with solvents in it.
My other experiment at the moment is with an acrylic floor wax that Home Hardware sells. It has a nice shine and goes on easily, I am just trying to find out if it has any potential for contaminating food.
Any advice would be greatly appreciated.
Erik
Beck,
I can't email attachments via prospero, so if you want, email me your home email address and I'll reply with a word.doc attachment that may be of some help.
Mongo
Hey Mongo,
Thanks for the reply, and I would love to get you my e-mail, except I only seem to be able to e-mail myself, (and I think that might make me go blind?) so if you can give me a heads up, I would appreciate it. (I swear I could build you a house, but can't really get much done on computers) Beck
Howdy,
I poured it off site with a melamine mold. It worked out really quite well. The only
thing that could have been better would be if I had less "voids". I went off a old
Fine Homebuilding article that said to mix it like "chunky oatmeal". If it were a little wetter it would have given better results.
Good Luck!
UpperHut.
What about a clear epoxy?
Clear epoxy tends not to stay clear, but becomes yellowed epoxy over time. If someone has found a real alternative to that problem, I'd love to hear about it.Formerly BEMW at The High Desert Group LLC
good info to know. We were considering sealing our basement floor (after staining) with a clear epoxy, but maybe that's not such a great idea now...
Like I said, I'm familiar with products that yellow; that doesn't mean that there isn't a better product out there that might stay clear.Formerly BEMW at The High Desert Group LLC
There's a fine line between too thick a mix and too wet a mix.
With thin slabs, you want to minimize water to maximize slab strength. Slab strength can be aided by substituting a latex ad-mix for some of the water.
Workability of the mix can be greatly enhanced by adding a plasticizer to the mix. It improves flow characteristics without having to add more water.
A good mix will still be thick enough to require you to work the mix onto the corners of the mold, as well as around mold obstructions, with a trowel or with your fingers. I use a wood trowel and fingers to work it into place.
Vibrating will consolodate the mix and minimize pinholes and voids in the finished slab. Again, a plasiticizer will allow the mix to flow better, minimizing the amount of vibrating that is required.
When vibrating, watch the surface of the slab. You can see the bubbles come to the surface. You don't want to vibrate too much, as you can send the aggregate to the bottom of the form, or, if it's not secured, cause the rebar (if it's not tied to the form) to sink to the bottom as well. If the rebar sinks and gets too close to the finished surface of the countertop, it can sometimes create shadow lines in the surface of the slab.
How much vibrating is enough? It's kind of like popping popcorn in a microwave. Keep going as long as the bubbles pop at a reasonable rate, but stop when they become infrequent.
Bryan,
You'll get more of a 'wet look' by using a gloss instead of a satin sealer, and also by using a film instead of a penetrating sealer. Plusses and minuses to both.
Fill the pinholes as Beck wrote...with a slurry of portland. Not too soupy or it will shrink and crack/flake. Or you can use colored 2-part epoxy clay.
saw your q's on here and thought i'd lend a hand. taunton press has a great book that will answer any of your q's and then some. try and do your next top using more ash in the mix and an elastasizer with a higher amt. of conc as well to counteract with the ash for strength. the mix is really thye key and should be a designed one not just some bags from home depot you throw together and pour in a box. if in fact that is what you did. but if you get this book all will be answered. you can also use plastic in your form for a smooth finish then wet sand it to the desired look you want maybe make up some chamfir for the edges. did you use any mesh in your top?
anyway seriously, read the book , it's worth the twenty odd bux.
Epoxy can give you a bullet-proof topcoating that will protect the slab from liquid stains and acid/citrus etching. Unfortunately, it undermines the utilitarian nature of the slab. With an epoxy film finish you really can't take hot pots out of the oven or off the cooktop and slide them onto the slab. The heat can either discolor the epoxy, or lift it off the slab. Impossible to easily repair.
Though I've not ever seen it, I did get an email from someone who had an epoxy finish ruined by a package taken out of the freezer that was placed on the slab.
I encourage people to use penetrating sealers, and to back up the penetrating sealer with a monthly coating of paste wax. You get a working surface that MAY stain if you leave damaging liquids on the slab for a few hours without wiping them up.
For molds, I line my mold with the cheapest, glossiest formica that I can find at the local home center. It can be reused for several slabs, and the glossy surface results in a glass-smooth, mirror-like surface on the eventual top of the concrete slab. Works better than anything else out there, and I do believe I've tried them all.
The worst thing about buying the formica is standing at the checkout line wth several sheets of ugly, unmatching formica, all the while knowing that everyone else in line is pittying my poor wife due to the dreadful looking kitchen countertops that I must be building for her.<g>