Advice needed - trying for a smooth finish w/concrete (PIC)

15 years ago

I'm making a mini modern indoor/outdoor fireplace out of concrete that will fit approx 3 votive candles. You can see my test here:

http://forums2.gardenweb.com/forums/load/hypertufa/gal0119004332072.html

This one turned out great as a casting but terrible in terms of finish & consistency, probably because I used cement instead of concrete (I saw "quikcrete" on the label and assumed that was the product, not that brand...oops!).

I also think the mix is off but am not sure if it needed more or less water. Seems like maybe more?

If you have any advice for a concrete recipe that will give me a smooth finish, I'd love to hear it. Also, are there recipes that will give you a more pourable concrete consistency? This mix was so sandy I really had to pack it into the mold to get it this good.

This is my first attempt so all help is welcome! And, I won't be using pure cement again, that's for sure.

Featured Answer

Belgianpup

15 years ago

I'm late in reading this, but if you still need some help...

When you first add water to your (proper) mix, just add enough to dampen all the ingredients, and mix it well. Then add a little water at a time until it is like a mudpie. You MUST mix it well, and your hands are the best tool (wearing latex or nitrile gloves). A little bit of water on the surface is fine.

For a quick test to see if you have the right consistency, press a handful or so into a regular paper cup, filling it about 3/4 full. Immediately turn it upside down and rap the whole rim smartly on your table to eject the contents.

If you can see any cracks in it, you either need a tiny bit more water, or it needs to be mixed better.

If it slumps more than just a little (a little is okay), you've got too much water in it.

Once you get it really right, you will know from then on. It's a practice thing. Just don't think it's going to set so fast that you don't have time to mix it thoroughly. Mixing is very important.

Press into your mold. For corners and details, put small amounts in first, then by double handfuls, pressing firmly into place.

Let set in the mold just long enough to set. Check frequently until your fingertip leaves just a slight depression. Unmold very carefully now, (it's still very fragile) to expose the surface you want to smooth.

Now, burnish the parts that will be visible with the back of a tablespoon/soupspoon/serving spoon (not the measuring type). If you want to carve a piece, this can be a good time to try it, too.

Pourable concrete is only used for large concrete work, patio slabs and freeway overpasses. I can't think of anything that we at this website do that will take that much water. Always remember that too little water, or too much water, will make a weaker concrete. It may not show up immediately, but it will do so eventually.

The 3:1:1 recipe above is best for most purposes; when you know more of what you're doing, and what effect you're trying to get, you will know better which way to go. Perhaps more more than any other material, mixing concrete is best learned by actually DOING it. Mistakes are useful for burying in the dirt along your gate-line to keep the dog from digging out. ;-)

Also be aware that there are different types of sand, and finer and more coarse grades. Sometimes sifted (by you) play sand is better than a coarse white silica sand. I find that sand with different sizes particles is a real headache to use. If I'm forced to use it, I will sift out the fine stuff and set the bucket of coarse pebbles aside for some future surface effect.

Have fun!

Sue

Sort by:Oldest

Comments (11)

gansn
15 years ago
Very cute idea. A nice mixture of 3 parts sand, one part portland cement, and enough water to make it a brownie dough consistency should make a smooth finish, assuming that your mold has a smooth finish. Water amounts can vary depending on the humidity, how much water is in the sand, etc. So start with much less than 1 part water, you can add more as you mix until it is the consistency you like.

Once you pour or spread your concrete mix, then use your hand or something to pat the concrete. You should be able to see it sort of liquify. This makes for a smoother finish. Slight vibration or bouncing makes for fewer air bubbles in the finish. Post another picture when you try again. I like the one you did though.

Glenda
0
billie_ann
15 years ago
DETAILS, we need details!! LOL!

Cement is an ingredient in hypertufa, concrete, mortar, etc.
Concrete is cement, sand and gravel. Unless you've got a mag trowel you'll probably see the gravel.
What recipe did you use, cement and water???
Are the cracks/voids in the side facing out in the picture the "terrible finish and consistency" that you're referring to?
0
Related Discussions
Fireplace redo-advice needed (and pics inc)
Q
Comments (24)
Dear fellow decorators, Thanks so much for all your responses! I knew I could rely on you guys. Thank you very much for the inspiration pictures, "jejvtr." I absolutely love them, and the look depicted in all three of them is pretty much spot on what I was envisioning. However, I am realistic and I know that our end result will probably not match what is in these pictures, because yes, the stretches of brick to the left and right of the main flank of brick are uneven. Also, I could remove the hearth, as you suggest, "egganddart49," but there are electrical outlets on both sides of the hearth, so I am certain removing the hearth would require electrical know-how, and DH and I are not up to snuff with that. I don't mind having the fireplace as the focal point, anyways-it's inevitable, and with a nice large painting above I think it can look nice. "Jakabedy," our house is actually a two story traditional colonial built in 1940. I do appreciate the MCM style, although our family room is not that. It was an addition consisting of a family room built on a concrete slab with a new master on top. I think whoever did it just took various elements popular at that time (floor to ceiling fireplace, large patio windows, wooden paneling, etc.) and mashed it all together. Cheers, Anna
...See More
'Almost Finished' kitchen pics- advice needed!
Q
Comments (32)
Frighteningly, I have a bird thing going in my house, too. Happened partly by accident (inherited mom's things) and partly as a response to the freaking Audubon party that happens on my lawn every day. I think it's the golf course nearby. Anyway, you need this picture frame in your kitchen, minus the unattractive married couple: There are lots of papers to explore besides Imperial Trellis. Neisha Crosland Majorelle in Mint, maybe: Ferm Living has some cute (Scandinavian!) paper: There's peekaboo from twenty2: You could maybe use Iconic panels, as long as they're not right behind the stove of course.
...See More
Kitchen Advice New Build (first-time homebuyers; w/pics)
Q
Comments (25)
Congratulations on your first house! It will be exciting to be part of a new community that is forming. - I agree that the natural finish cabinets are a good choice, but just for your own peace of mind, find out how much the upgrade to Shaker would be. Assuming Shaker continues to be a valued classic, that could be an advantage for you one day when you sell. - About that bi-level bar island...... It might seem like a great idea for adult gatherings, but if you need to talk somebody out of that, think about the future children using it!!! It's safer for them if the surface is NOT so elevated where they will be perching. Plus, there are many advantages to a one level surface so they can spread out their big pieces of artwork, craft projects, etc. They want to be near the person working in the kitchen, so make that easy for them and their stuff. - For the counters, did you consider the leathered finishes instead of the shiney ones? It looks like there are maybe four available at the link you provided, including this one which could be a happy combo with the natural cabinetry: https://www.chbriggs.com/pub/media/chb/Venetia-Cream-Leathered.jpg It seems like non-shiney might work better in a scandi-type vibe. In general, when man-made materials are imitating stone, I think the less obvious the pattern the better, so the ways in which the imitation falls short aren't in your face! Fortunately, your choices include a really nice option without a distracting pattern: https://www.chbriggs.com/pub/media/chb/Bianco-Pur.jpg - About the drawers, it really would be so handy to have at least one stack of drawers since there are so many small things in a kitchen to keep organized. Maybe use the cabinet to the right of the sink, as I am guessing from the handle that the one to the left is the trash bin? Personally, I think pullouts are over-rated, and a big un-constructed cabinet holds more (and costs less). Maybe you could see about switching one of the two pull-outs in the standard package to a 3 or 4 drawer stack. - Finally, flooring. It's nice that the same material will be used throughout the main level! But again, you have man-made materials imitating natural ones so you would potentially have to contend with the dissonance of fake wood floors next to real wood furniture and cabinetry, not just in your kitchen but in the living room and other space. Sigh. Thinking outside the box a bit, could you step aside from the floors trying to look like wood (and not doing a very good job of it) and go with one of the tile-like options instead? Those choices are quite limited at the link you provided, and all imitating travertine, a stone with a pretty dramatic pattern. I'd ask if other flooring patterns are available and see what upcharge there might be, if any, and try to find something with a pattern that won't be trying to dominate everything else you put in the rooms. Right now the market for LVP is mostly the fake wood patterns, so finding imitations of stone or ceramic tile is hard (I went through this recently myself!), but they are out there. Find a flooring store that loans out samples so you can take a piece home to live with it for a while.
...See More
Need advice on Kitchen Cabinets paint color; trying to modernize it
Q
Comments (38)
@Beth You did a commendable job explaining all the design aspects. Thank you so much! Just curious if I choose to change the granite completely, what color will go with oak wood floors and simply white or another white upper cabinets and darker island cabinets? I love the way island without cooktop looks. If I change then I won't be cooking any more :) Can you please give me advice on the kitchen blinds also? I am curious about the name of countertop and backsplash you have in your home?
...See More
concreteblue
Original Author
15 years ago
Thanks both for the help.

I used straight cement and water by mistake. I thought I had bought a pre-mixed concrete.

The cracks, voids and general crumbliness are the horrible consistency...I don't mind if it looks rough, but this looks more decayed than rough. I might be able to salvage it by resurfacing when I make an actual batch of concrete. But ideally I want a smooth finish and I may attempt to polish it if I can get past just making the thing correctly .
0
ladycraft
15 years ago
Concreteblue, I don't have advice but I like the looks of the fireplace. Wish winter was nicer so we cold do more projects.
0
gardengal70
15 years ago
This may not fit your situation but thought I would offer it anyway. I have made a couple sphere's by applying the cement mix to the outside of a ball. After removing the ball, I finish the outside using a mix of plain portland, water, some color and admixture. You need to experiment to get the consistency so you leave a smooth finish using your gloved hand. It is more liquid than the mix you are accustomed to using. Also must be sure of your proportion of cement to color because you need to make several small batches. Hope this helps. Marie
0
nicktexas
15 years ago
I would suggest using melamine forms. I have made a countertop on melamine, and it came out as smooth as granite, with only a few minor imperfections.
NickTexas
0
gardengalkc
15 years ago
Nick, I am curious about the melamine. How did you use to make a counter top? Thanks. Marie
0
nicktexas
15 years ago
Hi Marie,

When using melamine, you make the countertop upside down and then turnover. I built the form where I put a sheet of melamine on the bottom of the form, which ends up being the top of countertop. Even when doing it this way, there will be some holes due to airbubbles. I patch those immediately after turning the concrete over and allow a day to dry. Then using a sander or a polisher, smooth the top. The top will be as smooth as granite. After sanding, put on sealer, let dry, and then wax. Nick
0
gardengalkc
15 years ago
Just another thought, try using Quickrete Resurfacer, should be available at Lowes, Home Depot. The smoother the texture of your mold, the better. If You could cover mold sections with plastic wrap, you would have an even better chance but will have some lines in your surface. Even try aluminum foil
0
PRO
Concreteideas.com
9 years ago
I've used concrete in many situations for a decorative finish. To get it smooth you either need to form it in a smooth form and flip it over or hard hand trowel the surface with slight misting of water. I've also polished concrete before but it required some expensive polishing tools. I did a kitchen countertop before and got a super smooth finish with a high build epoxy coating - It was the enCountertop Concrete Countertop Mix with their enPoxy. It turned out great!

Here is a link that might be useful: Concrete Countertop Mix
0

Advice needed - trying for a smooth finish w/concrete (PIC)

Belgianpup

Comments (11)

gansn

billie_ann

Related Discussions

concreteblue
Original Author

ladycraft

gardengal70

nicktexas

gardengalkc

nicktexas

gardengalkc

Concreteideas.com

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

Advice needed - trying for a smooth finish w/concrete (PIC)

Comments (11)

Related Discussions

concreteblueOriginal Author

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

concreteblue
Original Author