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Pressed concrete finishing

58K views 232 replies 24 participants last post by  stonecutter 
#1 ·
I have a neat little fireplace job right now where I have to rip down some horrendous stone veneer and rebuild the raised hearth. I am building the hearth top with a hand pressed concrete top. I am doing this because the immediate area is completely lacking a good stone source. There is a small supply yard that has some stone (I got my veneer stone there)but no large flat stock. The pressed technique is a nice alternative for now...but I was wondering if anyone else crosses over into doing this kind of work. Also, I am going to seal the concrete and was curious what products you use or can recommend that are specific to GFRC concrete.

Of course pics to follow soon...
 
#2 ·
There are probably too many choices for sealers for decorative concrete. I normally use Xylexin for a tough, durable surface. This one has it;



Comes in gloss or matte finish. Kind of pricey but tough stuff. I'll have to hunt down the website if you're interested.

For really simple you can try a penetrating sealer and wax. This one was first treated with lithium silicate followed by an acrylic sealer then carnuba wax;



Easy on the wallet, easy to apply, but requires maintenance. Everything you need for this @ www.ConcreteCountertopSupply.com

Good Luck
Dave
 
#6 ·
Hand pressed is a technique used in some concrete counter top work and other decorative concrete. Normally used to create certain visual effects. The mix used would be on the dry side and hand pressed into your form. It leaves random voids on the surface which will be filled with a wetter mix of a different color.

The pieces I posted are wet cast, but the same sealers would be used.

Good Luck
Dave
 
#19 ·
Its a really exciting techinque to me because I always thought of concrete as boring....artisan concrete is far from it. If you are in a place like I am, with limited stone then this type of material expands your options. If not, then it still allows you to be really creative.

On this job I am using a premade mix by a company I stumbled across right here in SC. I visited their plant, talked with the owner and got what I needed. Cost wise it is a little more than doing my own mix but I can control it more...and since this is a paying job I didnt want to chance my own mix given my experience level. My sample is sound but this hearth is 8'.5" long...

I will share anything you want but you have to wait till I get this done so I can give good info!
 
#25 ·
Here's a link that can get you guys started in this sort of installation. Not quite as easy as it looks but the design benefits will let you compete with lick and stick if you choose to.

I've used in for retaining walls, fireplaces, chimney and house brick resurfacing and updating. Needs to be sealed every 3 years or so and of course you have to pay attention to detail.
 
#30 · (Edited)
So, this is the beginning. A little caveat before this starts... I am no expert like I said. Some of the things I am doing are not what seasoned concrete counter guys do. I'll mention that for relevant pictures. However the results from my samples have proven that the methods are sound and I'm comfortable with the results. O.K. here is what I have so far....


Melamine is a good form material because it can produce a nice finish and is less grabby than wood. Its still a good idea to use a release...I have heard about wd40, crisco, pam, wax etc..I used a little armor all.

To start with, I'm doing this back asswards because the hearth isnt even built yet. It would be easier to template a completed hearth but because of the steps needed for a press technique, I dont want to wait on the hearth after the stonework is done. So, this slab is a little bigger in width and I will cut it onsite...the length is going to be fine.

I laid out my hearth top on the melemine (4'x8') but my actual width for the top is 8'4". So I ripped a 12" piece and butted it on the end of the sheet. Then I taped the seam with scotch tape. When the counter gets flipped this will show in the form of a smooth shiney strip were the tape was...it doesnt matter, because I am wet polishing the whole thing multiple times.

I didnt want to handle a slab that large so I am making two pieces. The hearth top has a slight radius (for asthetics) so thats why I wanted to lay it out at once, then pour the two sides seperately.

Normally, you would no see screw holes on the inside of the form. But I didnt want to spend all kinds of time making angle braces to screw to the outside of my form. The thickness is 1.5" which is why 2x4's made perfect braces. The holes are filled with black silicon as are the seams on the bottom and corners. The holes are slightly recessed which will create a little "button" when the mold comes off. Again, it doesnt matter as I will be wet polishing multiple times. The 2x4s are screwed to the melamine base and that creates a tight mold. Heres the pics.




Automotive exterior Table Vehicle Furniture Car


Table Furniture Wood Floor Desk


Table Furniture Wood Plywood Desk


Roof Floor Table Wood Plywood


I am going to take the form apart on Sunday and press the other side so I'll document that next. Question time...:thumbup:
 
#32 ·
You could hot glue your sides in place. Set the face to your line and "caulk" the backside with the hot glue. Zip a trim screw into each corner joint for a little extra durability. Saves a bit of time and cleans off easy after use, saving your melamine for another day with no screw holes.

The real work will be after you demold. Seeing some of your other work, I have a feeling that will be no problem.

Good Luck
Dave
 
#34 ·
Zip a trim screw into each corner joint for a little extra durability. Saves a bit of time and cleans off easy after use, saving your melamine for another day with no screw holes.
You know, I have used wall ties as anchors for shelters during winter work. I'm thinking that a wall tie bent around the corner of the form and screwed to each side would really firm up the corner and stop me from worrying about movement. That, with the glue method..hmmmmm
 
#33 ·
Dom...good eye, it is 26" @ center and 25" on the ends. The hearth is not curved and I only wanted a subtle radius.

Dave, thanks for the tips...I have a really good glue gun too, just didnt think that it would be strong enough to hold the form. I do plan to reuse the melamine and just caulk the holes but thats a great idea. I have to admit that even though its probably the most important part, I hate layout and form building. I'm looking forward to the slurry coats and polishing.:thumbsup:
 
#35 ·
I just tried the hot glue on my last piece after reading about it on another forum. I was nervous when I started and impressed when it didn't budge while vibrating. Then it scraped clean with a putty knife afterward.

I didn't photo the form, but here's the work in progress;



Like you, I prefer to work the piece and will get my son to build the form when he's available. That hot glue trick is quick though.

Good Luck
Dave
 
#36 ·
I think I'm going to have to get on board with this. For years I have been mightily interested and have purchased a lot of the books etc....but have never followed through.

Maybe this thread will motivate me.
 
#43 ·
So this afternoon I got to unmold the first half of the hearth. The forms came right off with no problem and the concrete is curing nicely. My Dad came by and he helped me flip it over so I could see the top...I am very pleased with the voids and now I cant wait to do the two coat slurry to finish the veining. Here are some pictures of the first piece starting with breaking the mold down...

Table Furniture Wood Floor Concrete


Floor Wood Concrete Flooring Composite material


Granite Floor Concrete Rectangle Countertop


Floor Cement Concrete Granite Limestone
 
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