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  • OT question

    I am making a mold on my CNC router table in MDF. The image will be reversed
    so when I put in the concrete the positive will show when released from the
    mold. I am sealing the MDF with spar varnish. My question is.......what can I use as a release agent so the concrete will separate from the mold smoothly. Grease, Pam, silicone spray,WD 40 or whatever? I imagine I'll have to separate them while the mix is still green but set. Any ideas?
    These will be used for personalized stepping stones and such.

    Thanks
    Nick
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  • #2
    I use used motor oil on foundation forms
    also on smaller items I have used liquid soap

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    • #3
      When i worked in the bath tub factory we used silcone for mold release. Sprayed it on with a spraygun kinda heavy...Bob
      Bob Wright

      Comment


      • #4
        Having not tried this, and this is just a hunch, MDF is very smooth and I don't think there will be a problem with separating from the concrete. Unless someone knows for sure, if it were me I would make a little trial run before I started on the actual project. I have noticed better results when I tear down the forms on a concrete job when the concrete is a little green - like next day or so. You don't have to seal the MDF - it is a lot tougher than that.

        I just finished a house I built for my mother in law about 3 months ago. I did all the work from digging and pouring the footing, laying the steel, the masonry, framing, roofing, plumbing and electrical. The only thing I did not do was the sheet rock and the insulation. Most of the work I did with only one helper and a lot of the time I was working by myself. Except for the roof. the two of us did all the work.

        I really liked the MDF board. I got about 40 pieces as a going away present when I left the paper mill. I had never used it before and didn't know how easy it would be to work with. I made all the molding - baseboard, window, door and made the vanity out of MDF. I was amazed at how easily the MDF milled down with the router.

        Now I know this is off the subject - way off. But I wanted to brag a little and let you guys know what a real Black and Decker project is like

        Please don't beat on me too hard
        sigpic 6010
        If I had know I was going to live this long, I would have taken better care of myself.

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        • #5
          Most of the time I believe these concrete stamps are made out of rubber. I know the company I did a project at (I'm a PLC programmer) sold the stamps and they were made out of thick rubber.

          As far as something that won't stick? I'd almost coat the MDF (epoxy maybe) since it likes to absorb water and then use something like silicone. You could probably use about anything that you don't mind being on the concrete after you press the cement.

          Comment


          • #6
            Thanks for the replies guys.............I know MDF will swell up like a BALL Park Frank when it gets wet. The mold has to be used multiple times.
            Nick
            Miller 252 Mig
            Miller Cricket XL
            Millermatic 150 Mig
            Miller Syncrowave 200 Tig
            2-O/A outfits
            Jet Lathe and Mill
            Jet 7x12 horz/vert band saw
            DeWalt Multi Cutter metal saw
            Century 50 Amp Plasma Cutter
            20 ton electric/hydraulic vertical press
            Propane Forge
            60" X 60" router/plasma table

            www.youtube.com/watch?v=jTu7wicVCmQ
            Vist my site: www.nixstuff.com
            and check out some of my ironwork and other stuff

            Comment


            • #7
              Monte:

              You need some Form Release Agent. Used to be called Form Oil, or Form Release Oil back in the old days. There are two different formulations now. One is oil based and the other, more environmentally friendly, is water based. It was developed back in the day when almost all concrete forms were plywood, which is real "grabby" where concrete is concerned. Put it in a pack sprayer, spray your form really well, and you will get easy strip and multiple uses. I buy the stuff in fifty-five gallon drums but I am sure that you can get it in five gallon or smaller quantities. Call your local Ready-Mix concrete plant and ask them for a name of a local business that sells concrete accessories to contractors. Tell them you need some form oil, or form release oil. Stuff is relative cheap, non toxic, and easy to use. For me the oil based has always worked better than the water based.

              Adios-----

              Comment


              • #8
                Maybe I should have stated the forms are small..............say 18" square.
                This is not a high production form......
                Nick
                Miller 252 Mig
                Miller Cricket XL
                Millermatic 150 Mig
                Miller Syncrowave 200 Tig
                2-O/A outfits
                Jet Lathe and Mill
                Jet 7x12 horz/vert band saw
                DeWalt Multi Cutter metal saw
                Century 50 Amp Plasma Cutter
                20 ton electric/hydraulic vertical press
                Propane Forge
                60" X 60" router/plasma table

                www.youtube.com/watch?v=jTu7wicVCmQ
                Vist my site: www.nixstuff.com
                and check out some of my ironwork and other stuff

                Comment


                • #9
                  Around here, all the concrete guys use diesel . . . just put it in a regular pump sprayer . . . spray the forms just before pouring.

                  Comment


                  • #10
                    Hey Cal...........how about kerosene?
                    Nick
                    Miller 252 Mig
                    Miller Cricket XL
                    Millermatic 150 Mig
                    Miller Syncrowave 200 Tig
                    2-O/A outfits
                    Jet Lathe and Mill
                    Jet 7x12 horz/vert band saw
                    DeWalt Multi Cutter metal saw
                    Century 50 Amp Plasma Cutter
                    20 ton electric/hydraulic vertical press
                    Propane Forge
                    60" X 60" router/plasma table

                    www.youtube.com/watch?v=jTu7wicVCmQ
                    Vist my site: www.nixstuff.com
                    and check out some of my ironwork and other stuff

                    Comment


                    • #11
                      Originally posted by monte55 View Post
                      Hey Cal...........how about kerosene?
                      Unless we are on a Kerosene run for Turbine fuel or K1 all of our Kerosene goes into the Low Sulphur Diesel tank so the diesel could be kero or vice versia...Bob
                      Bob Wright

                      Comment


                      • #12
                        I had an old-timer friend that lined his wood with parafin wax before he poured concrete. He use to make cement bird baths.
                        I'm not late...
                        I'm just on Hawaiian Time

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                        • #13
                          Monte, I never heard of kerosene being used, but diesel is easy, cheap, and convenient. Guy you really need to talk to here is DDA52, or check SFT, I think he did a whole thread on concrete one time, do a search.

                          Comment


                          • #14
                            Thanks for the replies guys...............
                            Nick
                            Miller 252 Mig
                            Miller Cricket XL
                            Millermatic 150 Mig
                            Miller Syncrowave 200 Tig
                            2-O/A outfits
                            Jet Lathe and Mill
                            Jet 7x12 horz/vert band saw
                            DeWalt Multi Cutter metal saw
                            Century 50 Amp Plasma Cutter
                            20 ton electric/hydraulic vertical press
                            Propane Forge
                            60" X 60" router/plasma table

                            www.youtube.com/watch?v=jTu7wicVCmQ
                            Vist my site: www.nixstuff.com
                            and check out some of my ironwork and other stuff

                            Comment


                            • #15
                              Monte,

                              When we were doing a lot of concrete form work we used straight grease right out of the grease gun. Ran a couple of beads all over the form and then took a stiff bristle brush to spread it out. Any grease remaining on the concrete you're molding can be easily removed with Simple Green and a scrub brush.

                              The grease will also help protect the MDF.

                              Just one more option.
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