Concrete Picture Frame / Brutalist Sculpture
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Concrete Picture Frame / Brutalist Sculpture

October 17, 2019


There’s videos I planned to make which I’ve
literally left in the corner of the workshop for quite some time. This is one such example. The idea was to make a picture frame out of
concrete and this was the mould for it. I’m going to put a bit of this chopping board
oil in to try and reduce the likelihood that it will stick. You can also use Vaseline as a release agent,
or make the mould out of melamine backed sheet material or even lines the inside with parcel
tape. These were all good suggesting from my followers
on Instagram. The nice thing about using a mould made out
of real wood, is that you get the texture of grain on the final mould. You may have noticed this effect on some old
brutalist buildings which have used wooden shuttering to contain the pours. It’s very Scandinavian and very attractive. I’m going to use premixed patching cement
for this attempt. This mix will have a high amount of Portland
cement which will make the concrete set very hard, but also very quickly. The mix is 3 powder to 1 water and you always
pour water into the dry mix, and not the other way around. This helps prevent lumps in the mix. I use to have a trowel somewhere and I don’t
know where it is. I’m wearing gloves because cement is notorious
for f*%^&ing up your hands. Keep them nice and soft for you…tube. And if you want you can also where a dust
mask as well, in fact I’m going to put a dust mask on now coz I can see. The other thing to remember is cement will
not set if it is being agitated unlike plaster which sets when agitated. So keep stirring until you start pouring. I did my mould in several pours and also used
nylon fishing wire as a reinforcement. I didn’t get the mould out in time and as
it set, the concrete contracted and broke in all four corners. So I did what any sensible person would do
and stuck it back together with wood glue. Surprisingly that stuck quite well, but I
got too many air bubbles under the lip of the frame. I’m going to use this one to test a polyurethane
varnish finish on the cement, and remake the mould with a different mix. This is a polyurethane water based varnish. I’m going to use this to varnish the concrete
and get an idea of how it will look. There’s all sorts of sealers for concrete. You can even just mix waterproof PVA and water
together. For the second attempt I picked a different
brand of premixed concrete – mainly because it was on offer but also it has a medium range
setting time. It is a flexible floor leveller which means
it contains some kind of plasticiser to prevent micro fractures but also it must get mixed
to a runny consistency to act like a leveller. So this should get into all the corners. It was the only one between the two that I
could find. It was either an hour or 24 hour set time. Obviously an hour’s too quick and what happen
before was the cooling process meant that it contracted very quickly and formed the
cracks. I don’t want to leave it like a typical brick
mortar for 2-3 days to set and anyway that stuff is generally quite powdery so hopefully
this is a good inbetween mixture. 1000 ml of water per 5 kg. So for 4 kilos I need about 800 ml. I used corner brackets this time, along with
the nylon thread to reinforce the concrete. I also drilled a few holes into the top of
the mould so any air under the lip could be released, but the mix was a lot more runnier
so I may not have had to do that. Anyway to cut a long story short I broke this
one as well so lets move along to the third attempt. I think I’ve made a piece of art work, and
I’m not saying that sarcastically. I think I have. Ok I’m going to have one last go at this. What I’m going to do is clean up the mould
and reassemble the outside as I had before, like that. I’m going to change this a little bit. I’m going to cut away maybe in the centre,
just so that I can dismantle this a little more easily. I scrapped and hoovered, oiled and reassembled
my mould. This time I
used hot glue to hold the central pieces in position. I’ll be able to pull these apart without
having to unscrew anything. I am going to take the mould apart before
the concrete fully sets as well. I should have cut these at a slight angle
to make it easier to pull these out. But it’s pretty straight so I shouldn’t have
a problem. If I’d done it the opposite way around I wouldn’t be able to pull it out. Ok I’m going to wait about 10 to 20 minutes
while this starts to thicken up. I’m going to pop the bits of metal in just
to reinforce it and the corner brackets as well. This time I’m going to make sure these go
a lot closer to the inside edge than the outside, because if a little bit chips out here you’re
not going to see that on the inside. These are starting to feel quite hard so I’m
going to try and open up the mould. At least the central bit. I’ll leave the outside as it is. I think I might leave this bit exposed so
you can see into the frame while it’s up. Ok it looks pretty good. There’s an ever so slight hair line fracture
there but it’s kinda held. And that hasn’t gone through to the other
side. There was a few places where the cement had
broken off, and that was more to do with how I was dismantling the mould. You can see a little bit there, and another
section there but I was able to glue them back. This particular mix was a little powdery than
the first one I did which is down here. You can also see a slight difference in the
colour, despite that I varnished this one it’s a lot more greyer. The other two which had a slower set mix,
which means there was less portland cement in there. They look a bit more sandy. It got a kinda greeny yellow colour to them,
which is basically the builders or sharp sand. I think if I do this again in the future I’m
going to make my own mix and what I’ll do is use sharp sand. Maybe 2 sharp sands for 1 portalnd cement,
or or maybe even 1 sharp sand to 1 cement. I think I’d get a better colour as well. Now I could, if I has some cement I could
just mix that up with a bit water and maybe brush that in see if that binds and hide some
of the imperfections but I don’t, and I’m not planning to go down to the DIY shop for
a little while, so I think what I’m going to do, like the first one is paint it with
polyunsaturate varnish. I think it needs a few coats, and what I need
to do is, sand it back band hand after it’s dried. Just because the brushing process has lifted
a bit of grit and dust off the surface of the concrete, and mixed that with the varnish. I think the finish could look a little bit
nicer. Still not too happy with the colour of it. It looks too wet, too green. I much prefer the colder look of the mix with
more portland cement. Once you put int his case the plastic in,
you can see the depth of the frame is a little too large. But there’s plenty of room to place a piece
of work, a drawing or something and a backing board, and obviously you can’t tack it as
you would normally do with a frame – you would have to probably use silicone sealant or some
kind of glue. There other things I need to think about in
terms of hanging, and finalising the mould so the ratio looks a bit better in terms of
depth of the lip to the actual depth of the frame. But as a test of the principle whether it’s
possible to make a rectangular frame with a rebate out of concrete – it seems it’s possible.

Only registered users can comment.

  1. Maybe like metal casting, the mold needs some small angles and not 90 degrees to help with removal. My old brain cant remember the term but you'll get the idea.

  2. you need constant vibration, don't you?
    like a drill with a very off center piece of plywood attached to the bit left on while the tool is in contact with the frame

  3. use fibers, mix of sand and cement 3:1 and water 0.5 – 0.7 from cement and use vibratory grinder for compaction. Can be reinforced with a wire 0.5 – 1 mm around the perimeter. Waiting 24 – 48 hours.

  4. I think you're having a problem "pulling" the form from the concrete.  Normally, people add "draft" to the form to allow pulling  without damage.  With straight walls, the bottom has to past the top and move in a straight line without hanging to avoid damage.  If the bottom of the frame is smaller, that's not so much of a problem.I'd suggest using 5 degrees on the surfaces that the concrete touches; in other words, the bottom of your mold would  about 1/4 inch (6mm) smaller than the top (based of a 1 1/2 inch (38mm) tall frame.  That way, as soon as the mold started to move up it would be free of the side walls and be less likely to hang.

  5. Interesting project! Got me thinking about a picture I have that needs a frame that's out of the ordinary.

  6. Came to think of your channel today and thought "why doesnt he put up videos anymore?" I used to get the updates on my phones. Turned out the bell was unchecked. :/

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