Re: Concrete formula for casting in molds
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
news:20040703211601...@mb-m28.aol.com...
> X-No-Archive: Yes
>
>>
> Lately I have been considering looking into concrete. Molds I am
considering
> offering casts in concrete are open back Polytek 74-30 with some undercuts
and
> lots of detail. Ihave slush cast one mold years ago that was of a large
bust
> www.lostnewyorkcity.net
>
>
Hi Randall - great to hear from you. Like Ethan in NYC - you have problems
getting the more exotic materials that casters have to deal with. Sacrete is
an ok product - the masonry readymix is usually 1 part cement to three parts
coarse sand. But this is not a real sharp (more $$$) silica sand, and the
concrete powder is a general grade, grey in colour. As you have found out,
the usual problem with concrete is its weight - cheap to solid cast, but
expensive and dangerous to move about. Check the sakrete website - there is
a book too - kind of neat, it has the actor "Mr Limpet" (Wally ??) on the
cover - sort of like 'even a geek can work with sakrete'.
State of the art concrete - but probably much more trouble than it is worth.
Facemix with white cement/ white sand - fifty/fifty - use a mold soap and
carefully brush in the facemix. Backing mix with fibers while the face is
still wet - high strength/low weight is the key here - so we strengthen the
cement with flyash, acrylic resin, and as little water as possible (using a
superplasticiser). This should be about 1/2 to 3/4 inch only - make sure to
cast in the metal hardware.
This actually still isn't 'state of the art' - there are some new concretes
coming out of europe now that are super high strength - here's a link of
interest to sculptors and visual artists too
http://popularmechanics.com/science/research/2002/6/concrete
Happy July 4th by the way. Heres a patriotic link for the statue of liberty
(so it is sculpture related) and make your own 'digital' fireworks
http://www.njagyouth.org/Liberty_.htm
I'm off to visit Randall's great website now.
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
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>
>> I just had a thought from your post! Sakrete does have somewhat course
sand,
> yet I know someone who obtained a dozen or so bags of some very fine sand
used
> in his sandblasting gun, I think they were 50# sacks and I'll bet anything
he
> got them from Mendards. I think I'll look into that sand and try mixing
it 1:2
> as you suggest below, should be a good strong mix using the locally
available
> Portland cement.
Good sand is real important for cement, because cement itself is rather
weak. Even 'high strength' concrete is only 6,000 psi.
>
> What can you say about that superplasticiser and where to get it?
> I'd have to use rubber gloves to pack the cement into the face of the
mold, the
> stuff is wicked on skin otherwise. I never bought mold soap but over the
years
> Ive always used Murphy's oil soap on plaster mother molds, and on the
Polytek I
> do have some of their spray release called Pol-Ease
The oil soap is good, the pol-ease is probably silicone and hard to paint
over. The smooth on has 'in and out' solution, I think it is the same as oil
soap without the fragrances and chemicals (which may be harmful to the
rubber if you are in high production. Cement is hard on molds - alkalinity
and sand. Superplasticizer is pretty common with the concrete suppliers -
you don't need very much, it is like a soap powder. Of course lime putty is
the best plasticiser - but it slows done the demold time considerably.
I have two new products which I will be launching on my eshop. The first is
a foam concentrate and spinner kit to make your own casting or carving stone
from hydrostone, drystone or cement. The second is a gelatine mold material
(this is the reason for delay, I'm still working on it) that you melt and
pour over the sealed model. It is only good for two or three castings, then
you melt it down and reuse it. It is great for our type of work because you
can make a casting master (storing the original) without using expensive
silicone rubber, and can cast a few pieces without the expense and fumes of
polyurethane. If you find everybody in NYC wants a cast, then you can
upgrade to a production mold system. The foamed cement is used like you
described with the slush mold, a hard face mix, then foam backup. The foam
is also used to cheaply and lightly fill a handlaid casting - for some
reason people do not like hollow objects.
You should look at getting access to a small kiln, and casting glazed
terracotta pieces - people will pay a lot more money for this, it looks
better, have unlimited colors. To eventually get into your own kiln is no
big deal either - although 240 volt is better. Commercial production is also
easy to accomplish by subcontracting to someone. You already know a lot
about terracotta. A hand glazed terracotta keystone, made the same way as
the heritage piece, should retail for about $149?
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote
Randall - did you put glass eyes in one of your lion casts - I always wanted
to do that? I sent in once before someone made a fake stone plaque for a
haunted house, it has a motion sensor, and the eyelids open, glaas eyes, and
it triggers a cd player or cassette. Best part is that it is all made from
that "Talking, Animated Douglas fir tree" you see around Xmas time (used -
about $30). I'd bet that would sell well in NYC for the rich - and gets lots
of free publicity too.
I could look up the link if you want.
Lauri Levanto
Gary Waller wrote:
> "Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
> news:20040704133645...@mb-m06.aol.com...
> (...)
> You should look at getting access to a small kiln, and casting glazed
> terracotta pieces - people will pay a lot more money for this, it looks
> better, have unlimited colors. To eventually get into your own kiln is no
> big deal either - although 240 volt is better. Commercial production is also
> easy to accomplish by subcontracting to someone. You already know a lot
> about terracotta. A hand glazed terracotta keystone, made the same way as
> the heritage piece, should retail for about $149?
>
>
Hi Gary,
I have done small sculpture of unglazed terracotta and white clay.
Glazed objects are here (in Finnland) regarded as ceramics, not art.
The glaze also smoothens out details (but you can compensate with colors).
White or cream color pieces sell better than red here.
I do both slip casting or handlaying into a piece mould.
http://www.netti.fi/~laurleva/more_sculpt.html
During the last two years I have been obsessed by casting into glass.
-lauri
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
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>
>
> Glass eyes??? Gary LOL that sounds pretty funny though as I know those
Haloween
> door trees you speak of!
> Nah I don't think I'd want to do that :)
Under 'sculptures for sale' fifth photoset down, the lion on my far left
(looking at the screen)?
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
> X-No-Archive: Yes
>
>> Hey Gary, you know Polytek has a couple of mold materials somewhat
similar to
> that, a geletine and a wax you melt down and re-use. I've considered those
for
> the times where I have a larger block and just want to mold part of it.
The big
> red cornice lion I have from the YMCA in NJ is like that. It's a large
block
> about 20" deep and 3' wide and would be nice to reproduce just the center
> section with the head.
I couldn't find gelatine on the polytek site. It is different than wax.
Another method is 'squeeze molds' - I use it all the time. A nice water
based potters clay that is allowed to dry to a stiff putty, but not sticky.
Dust the model with talc or chalk or calcium carbonate, press the clay onto
the surface. Make a light shell with plaster and fiber. The whole thing
removes carfefully, even a bit of undercuts are OK because you have t he
plaster shell to fit back into. Pour plaster and a bit of lime into the
clay. The lime gives you time to recarve the plaster before it fully sets.
Practise makes perfect.
>
> I have thought about that idea many times over the years, might work with
> smaller pieces, the larger pieces like keystones or that lion which as
terra
> cotta weighs 300# are probably too big for most kilns. As you remember
from
> that book I suggested, those were all hand packed into plaster piece molds
and
> the clay had a lot of grog, course grog and the walls averaged 1" thick.
That's
> pretty heavy stuff mass and wall thickness wise which would need an
especially
> long pre-soak period and careful temp control up and down so it doesn't
crack
> or explode.
Architectural terracotta seems to have a weight limit. It was mean't to be
handled by one or two workers - there were the savings. Anything too big was
broken into smaller chunks. There were some very large pieces though - but
kilns that size are long gone. Also the advantage of by foamed system is
that we are talking about a two hour 'surface glaze' , low temperature,
rather than a complete firing like in terracotta. My buddy has two ancient
electric kilns he bought at flea markets - I 'll have to check them out.
Lauri knows a lot about this. I know how to make my own refractory walls
too - so size would be too much of a problem
>
> check out my message board forum for the topic "keystone" way down at the
> bottom of the list. She is about 27" long, and this was... are you ready?
>
> $950.00 plus $200.00 for truck shipping in a crate, should arrive in about
a
> week or so.
That seems like a reasonable price for the original. Very Victorian - I
like it - a lot of those sort of images here. If you want to sell
reproductions, you gotta get the weight down to about 30 lbs. This is doable
too. I am toying with the idea of making polystyrene vaccum molds (like
those clear food product blister packs) then fill with the carving foam.
Then you have your shipping container too. I would encourage hand carving
with Dremel though - no undercuts can be included with this technique.
> That 600# concrete repro I made is pictured on Plate 4 of the sculptures
page.
>
> I also bought if you didn't see it, a cast-iron piece from the West Side
> Highway- the design is the round charter seal of NYC with the 1664 date,
latin
> inscription, Pilgrim, Indian and Eagle. Those now run around $700 when you
find
> one- the highway has been gone many years.
> I inquired about reproducing that in grey iron or bronze and I got a
pretty
> good estimate.
>
> Hanging something like that would be interesting, the originals were
bolted
> from the back. I had to weld up a bracket to hang mine.
Some gorgeous pieces. I would love to be able to reintroduce that level of
work to architectural market.
Here's another thing I have unique knowledge on - because the fresco panels
I make are so damn heavy. There is a type of lift designed for drywall
panels that can lift up to 350 lb panels, up to 20 foot. I was going to rent
one and then weld a custom one. They are usally avaliable for rent from the
big drywall supply stores. The wall side is easier, this weight is not too
much problem but some planning is needed.
Gary Waller
"Gary Waller" <moz...@telus.net> wrote in message
news:Qv4Gc.59418$_5.22352@clgrps13...
ps randall - good to see to didn't blow your hand off or put someone's eye
out with celebration fireworks!
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
> X-No-Archive: yes
>
> << Under 'sculptures for sale' fifth photoset down, the lion on my far
left
> (looking at the screen)? >>
>
>
> something must be mssing from your post or mine- what is your question or
> comment on that square lion? Or was that the one you were thinking of
having
> glass eyes?
>
Yes - the square one - obviously I am wrong - it just looks that way in the
photo - and no - I haven't been smokin' anything. I guess there is a fleck
of white on the photo which gives the impression of shinyness - classic
painter's trick.
howard & margaret
of my site on google search engine www.artspark.com.au M.Sparksnews:smVFc.104217$E84.88685@edtnps89...
Andrew Werby
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
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>
> Hey there Gary,
> I finally got around to trying some concrete yesterday, I bought a sac of
type
> 1 Portland (all they carry) and a 50# sack of that fine quartz sand used
for
> sandblasting, actually I remember that white fine sand being used in
commercial
> cigarette ash trays in office buildings :)
[Sandblasting with quartz (ailica) sand has been illegal in most places for
a while now, due to the danger of rapid-onset silicosis. If you look at the
bag, there should be a warning about this on it. Here's a short article on
the subject from the CDC: http://www.cdc.gov/niosh/92-102.html ]
>
> I mixed it 2 parts of sand to 1 part of portland, I figured I would try a
> somewhat liquid mix and got it to around a thick pancake batter
consistancy.
> Poured it into a small open back mold, jiggled the mold and took an old
> toothbrush and probed the inside of the face to dislodge any air bubbles.
> I carefully removed the cast around 6 hours later and it came out super
nice,
> no surface defects at all.
> This morning I bevelled the back edge and it seemed to be just about as
hard
> as hydrocal to do that with a knife.
> It's now wrapped in a plastic bag where I'll leave it till next Saturday
( one
> week)
[You can put some damp cloth in there to help it cure.]
> I think on larger pieces with undercuts that are more resistant to
demolding
> easy, that concrete may have to stay in at least over night or I would be
> breaking corners and stuff off demolding so soon-it's pretty green after
only 6
> hours.
[Yes, that would be wise.]
>
> I didn't add any color to the mix.
[That's something else to experiment with. You get brighter colors if you
start with white Portland cement - it avoids that gray-green tinge usually
characteristic of concrete. There are also colors that can be used on the
surface after unmolding. ]
Andrew Werby
www.unitedartworks.com
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
> X-No-Archive: Yes
>
> Hey there Gary,
> I finally got around to trying some concrete yesterday, I bought a sac of
type
> 1 Portland (all they carry) and a 50# sack of that fine quartz sand used
for
> sandblasting, actually I remember that white fine sand being used in
commercial
> cigarette ash trays in office buildings :)
>
> somewhat liquid mix and got it to around a thick pancake batter
consistancy.
> Poured it into a small open back mold, jiggled the mold and took an old
> toothbrush and probed the inside of the face to dislodge any air bubbles.
> I carefully removed the cast around 6 hours later and it came out super
nice,
> no surface defects at all.
> This morning I bevelled the back edge and it seemed to be just about as
hard
> as hydrocal to do that with a knife.
> It's now wrapped in a plastic bag where I'll leave it till next Saturday
( one
> week)
demolding
> easy, that concrete may have to stay in at least over night or I would be
> breaking corners and stuff off demolding so soon-it's pretty green after
only 6
> hours.
>
>
I have been casting with the new pva-eec system - I know, another acronym.
This is basically fibercement made with pva fibers rather than alkali
resistant glass fiber - the verdict is - they are wonderful! You use less
than glass fiber, they are less stiff, they are stronger, and any loose
threads burn off. They are now exclusively available from nycon.com - they
are just gettting them up on their website, and will be pushing them over
the glass fiber - they are $3.80 us a lb minimum 40lb bag, plus shipping.
Basically the glass fibers are proven/made in Europe, the PVA fibers are
proven/made in Japan. They are made by kuraray. The other nice thing is if,
like today, you have to grind the cement - there are no glass fibers in the
air. The mix is like a stiff 'cow patty' that you can hand pack into a mold
as little as 1/4" thick. Then I am hand glazing everything to look like
terracotta. Will be starting some giant ionic capitals next week. The local
smooth -on distributor wanted $17.00 a lb cdn (!!!) for AR glass fiber for
their duomatrix c concrete casting system.
I also add acrylic latex and superplasticiser to this hand cast 'cow patty'
mix.
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
> X-No-Archive: Yes
>
>>
> I think a tint and then a stain wash after demolding is what I'm after.
Most of the sandblasting today uses a combination vacuum cleaner and
blaster - it gets sucked up as fast as it goes out, and they are not
expensive units. Sandblasting and pressure washing is sort of frowned on by
the restoration people because so much damage has been done in the past, but
it is a productive and powerful tool in the right hands. A few years ago,
some city workers were sandblast cleaning the concrete base of a public
bronze statue, it was doing such a good job that and then they decided to
'have a go' at cleaning the 'dirty' bronze too! Luckily they were stopped in
time. I would use live steam (vapor cleaning), nonalkaline 'soap', and
nonalkaline microcrystalline wax to seal and protect.
You may be unable to buy bags of white cement (home despot stocks it here)
but New York is where I buy professional concrete and lime pigments. Heres
the link http://kremer-pigmente.com/englisch/cement.htm. Maybe get one of
those sliding 'color wheels' from the art store too - how to add and
subtract colors. Kremer also has sample sheets of the colors too. Get some
potassium silicate from kremer. Mix it with lime/concrete pigments and about
2 to 3 parts water. Best concrete paint/stain ever - and absolutely no
smell.
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
> X-No-Archive: Yes
>
> Great link Gary, looks like they have LOTS!
Some of thise is pretty expensive though - try to stick to the oxides if you
are interested in earth tones - they are the cheapest. Pure colors
especially with anything 'mars' in the color.
>
> So here's another question, with 1 part Portland to 2 parts of sand giving
the
> final mix a strength of "x" would going to a 1:1 add any strength beyond
that?
>
> I know straight Portland is weak but wonder about a 1:1 or 1:1-1/2 ?
>
>
This is the point of the 'superplasticiser' - it enables you to skimp on the
water, making a stronger mix. As far as setting time, there are so many
variables. The plasticisers are in a cheap packet, designed for hundreds of
lbs of concrete - the only downside - they smell like cat pee - but maybe
thats the secret ingredient? The grit sand to cement ratio is much more
difficult - remember I can make concrete with no sand at all - just foam
bubbles - but portland cement is weak and it shrinks - thats why the sand is
there (the magnesium oxychloride cement, hydrostone or drystone do not). You
may have to layer something like this - a 'face mix' made 'rich' with cement
and fine sand, then a backing mix with more sand, and a coarser sand, for
strength and can take the cracks, then a filler mix with even more sand (or
perlite or ground styrofoam). If you are not going to use 'concrete bonder'
then all these layers must be done while the concrete is still 'green' - we
often add an accellerator to the 'face mix' so it is starting to setup by
the time we have mixed the 'backing mix'. If you are going the other way,
building up the layers towards the face (not in a mold - like over an
armature) then we sometimes add a 'retarder' so the cement is still green by
the time we trowel on the final color/low sand layer. You are definitely
have to visit a local concrete trade store - but you shouldn't have to spend
over $20 for all these exotic additives.
You can easily spend $20 at kremer - but you would then be making colors of
concrete never seen before. I have also successfully tested some glow in the
dark colors(swimming pool blue) and some remarkably shiny glitter flakes.
The concrete store will also sell 'grouting bags' - usually used by
brickies - you can experiment with 'doodlecrete' - thats when you squish out
like cake icing into a face mix or slab. I saw an picture of a building in
the uk - the doodle swirls were in ultramarine blue, and the concrete was
white, and then the whole surface was ground/polished with a water feed
diamond grinder. Beautiful, inexpensive and timeless (it was the beams of a
new law library). The use of concrete by artists should be widespread,
working closely with architects/engineers - but it is not - there is too
much distrust and egos between these two realms. People I know who have
successfully bridged the gap have years of well paid, high profile work at
hand - they end up getting much more than the 'public art' crumb, they get a
whole cookie.
I'm going to make an urban cementhead out of you yet Randall! I know it
sounds kind of anal - but keep a casting journal noting temperature/time
etc. This eventually comes like an instinct - but you may not have the time
to develop this skill (an apprentice mason), so you must rely on your notes.
I would brush (or spray) in a nicely colored 'face mix' - about 1/4 inch
thick, and then back about 1/2 to 3/4 inch with the 'super' cement made with
pva fiber, acrylic, plasticiser and sand slapped in by hand (wear a heavy
rubber glove of course), cast in some stainless steel hanging hardware, then
stain with the pigmented silicate if desired. The total weight would be
about 8 to 10 lbs a square foot, and it could handle any weather - even glow
in the dark underwater if you want.
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
> X-No-Archive: Yes
>
>
> Gary, did you ever use that Sculpture House® Vaitcan Art® casting stone?
>
> It came in a leather brown, a terra cotta red/orange and maybe a jade
green
> color as I remember. It came in a 25# box and was pretty expensive
compared to
> hydrocal in 100# sacks elsewhere.
>
> It had quartz crystals in it which gave the casts a little sparkle almost
like
> brownstone has, it was pretty nice but once I didn't stir up the quartz
enough
> and it settled in the face of the mold and just crumbled off. I was unable
to
> get hydrocal that dark a brown or red.
>
I know about it - but never tried it. Gets those mars oxides and you will
have no problem tinting those vibrant colors. Some of the pigments are
metallic salts and they will accelerate slightly gypsum (but little effect
on cement). I used to use zircon in my face mixes - this is a cheap
blasting/polishing grade of industrial diamonds - don't try to drill or saw
it though.
Ethan Gross of NYC was sperimentin with all this stuff too - he took that
scagliola course at kremers - haven't heard from him for a while?
Dan S
find in NYC. Most dealers probably have to buy an entire pallet of wht
port or HCal to get it at all so try to interest others in it too.
Blue concrete tint turns out to be crushed lapis lazuli! Darn right it's
high. Confine expensive colors to your facecoat. You knew that.
Speed of cure? Temp of ingredients, mold, ambient.. more cement vs more
water.. vibration characteristics.. sunshine.. have fun.
Dan
--
Dan Spector
http://www.archicast.com/Lifecast-index1.html
----------
In article <20040817140138...@mb-m29.aol.com>,
lostnew...@aol.comcomnet (Lostnewyorkcity) wrote:
>
>
> X-No-Archive: Yes
>
> Hi Gary,
>
> I think a local lumber place cen get the white portland for me, I just called
> and asked them to get me a couple of bags to try.
> They might be able to get hydrocal too I hope!
>
> I just spent $17.95 x2 for 2 fifty # bags of hydrocal, plus whatever UPS will
> be as I need it NOW and have been waiting on a place down South 2 hours away
> that has a delivery route up here but only on an as needed basis once a week.
>
> So far they have had no deliveries up here the last 2 weeks, so I'm waiting on
> them still...
> They have a $50 delivery charge (was $35) so that probably killed a lot of
> their route off.
>
> They aren't open Saturdays so I can't drive down and get the stuff, nearest
> other place is open Saturdays but also 2 hours away.
>
> Hope to get some of that Mars Red you mention
>
>
>
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
> X-No-Archive: Yes
>
>
> <<
> I'm paying 18.50 per 100 lbsack for HCal. Cannot possibly be hard to
> find in NYC. Most dealers probably have to buy an entire pallet of wht >>
>
nearest
> decent sized town which has only about 15,000 people in IT. People around
here
> in pig farm country - the lumber places etc never even heard of hydrocal
and
> haven't a clue, so that's what I'm up against.
>
Sorry Randall - I too thought you were an urban peasant (artisan class) too.
Moved to the country eh - I know someone who did this and couldn't sleep for
a month until they brought a tape of nighttime urban street sounds! Maybe
try the usg.com or georgia pacific.com (their densite is better than
hydrocal anyways) - and look for distributors. So when I mentioned the new
USG 'drystone' you had never heard of it. It is a new upgrade to hydrostone
which dries to painting/staining ready real fast. Drystone is now the
hardest plaster.
Dan S
----------
In article <1lRUc.37675$fz2.15429@edtnps89>, "Gary Waller"
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
> X-No-Archive: Yes
>
> Hey Gary,
>
> An update I guess, I got hold of 200 # of white portland and found a
couple of
> bottles of liquid cement colors by Quikrete®
>
> The red I didn't add much but it made the concrete much weaker and still
dried
> almost pink.
>
> I also found an issue I didn't like- namely cross-contamination of colors
is
> real easy!
> I decided to re-think coloring the stuff, or at least maybe coloring only
the
> buff yellow not the red etc. I'm more in favor of concrete STAINS which
will
> vary in tone like wood stain does, that would be closer to the effect I
want.
> The colorant made the casts look pretty bland and even colored like they
were
> painted with flat house paint.
> Even if that worked well I would STILL have to stain to get what I want.
>
> Seems like leaving the cast in the mold for 12 hours gets it hard enough
to
> demold without breaking things. I'm using a 1:2 ratio, I'm wondering if
you
> know where the cut-off point is? in other words at what ratio would adding
more
> portland to the sand not make the casting any harder/stronger and in fact
start
> to decrease that aspect?
>
> Id like them as hard/strong as possible of course, so is a 1:1 ratio about
at
> the cut-off point?
>
>
I think I explained earlier, you can vary the cement to sand ratio according
to where it is in the cast. The unavoidable fact is that cement (the powder)
shrinks and has very little strength without the sand/aggregate/fiber/metal.
It also depends on the quality of your sand - a good 'sharp' silica sand is
much stronger than say 'playground' sand from the hardware store. Also less
water makes it stronger, also acrylic latex. No mix is ever exactly the
same, and can even vary day by day. This is especially true for the custom
work and sculpting mortars - I guess if you were precasting stepping stones
in a factory it would be the same everyday though. To get high production
you use wet, pourable mixes and a vibration table. A table would be a big
help to you, as well as one of those vertical pan mortar mixers (can mix
cement and stiff mortars).
The pigments may have retarded the cure rather than weakened the cast -
check them again to see if they are now strong.
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
> X-No-Archive: Yes
>
>
> For masonry, sidewalks, slabs, brick work etc shrinkage would be a
problem, but
> on a garden sculpture or hanging wall decoration shrinkage wouldn't matter
> unless it had to butt up against something and fit well like a multi-piece
> fountain.
The problem for us casters is cracks - which can show up weeks after the
casting. The sand stops the shrink and the cracks.
>
> Need to do that now because I plan to stud wall and insulate the
exterior
> foundation wall along there before I can put in a 24' long work bench with
> storage below it.
Now I have a vision of you as the rural homesteader! Not planning on keeping
goats are you?
> I'm looking into a small electric cement mixer, I won't be mixing more
than
> maybe a 5 gallon pail worth at a time since it takes some time to pack the
> molds and all that with working time of the concrete in mind.
If thats all you need, don't bother with a 'mini' mixer (mean't for 100 to
300 lb batches), just get a 3/4 inch electric drill, and a good mixing
paddle. I like the one called 'jiffler'
http://www.continentalclay.com/Product.aspx?ProductId=537&CategoryId=333
(available lots of places). For the stiff stuff though you have to take it
to a welder and get them to spot weld the paddles to the shaft - this mixer
wasn'nt mean't for the stiff stuff, but works well with this modification.
Get the biggest one.
>
I have never tried those liquid colors. Davis makes some dry pigments, but
still the best is the oxides from kremer - look for ones with high tinting
strength. The only purpose in pursuing these experiments is to maybe come up
with a custom color which identifies your product. A color I really like
(right now) is ultramarine blue (stabilised for concrete/fresco) and raw
umber - its a unique light blue, warm gray when mixed with white concrete or
plaster.
Are you going to relaunch your line of reproductions? Maybe we can
collaborate on something? This foamed magnesium oxysulphachloride cement I
am working on will dominate the market. Lightweight, strong and it can take
a genuine ceramic glaze (apparently, still getting some samples prepared).
Gary Waller
"Lostnewyorkcity" <lostnew...@aol.comcomnet> wrote in message
> X-No-Archive: Yes
>
>>
> I actually have one of those, but I think trying to mix concrete with it
in a
> hand held drillwould burn up my drill pretty quick. I also imagined it
would
> introduce a fair amount of air, I have a large one and a small one, the
large
> one when used in a bucket of hydrocal tends to just push lots of air in,
too
> much turbulance so I use the smaller one.
Actually the best is a geared 3/4 inch drill - like the milwauki 'Hole Hawg'
. I use an ancient geared drill that I rescued from a pawn shop - it must be
from the forties - Black & Decker model 45 - it must weigh about 20 lbs.
>
> I like the idea of the concrete mixer since I can just dump the sand and
> portland in, let it mix while I do prep work like wetting molds, and then
when
> I'm ready add the water, and while that mixes up turn the molds back over
and
> check them.
> I'd also use the mixer for some more slabs out back I need.
I thought I had a good setup for you in New York - but it looks like the
mixer has been sold
>
> The way I was taught to do hydrocal in 1978 was you get the molds all
dunked in
> a 55 gallon bucket of water and leave them to drain the residue over
their
> mother molds. Then fill the 2-1/2 gallon bucket with water, add in the
> hydrocal- we did it by hand and you quickly developed a "feel" for the
right
> mix consistancy and let it soak. While that was soaking we turned the
rubber
> molds back over and inserted them in their plaster mothers, then the
bucket was
> ready to mix.
>
> Poured that in a table full of molds to about 3/4 full, and then you got
the
> air bubbles out of the face of the molds by hand/finger tips probing and
> rubbing around inside and then filling the molds up, screed the tops level
and
> by then the pieces were starting to get thick enough to embed the wire
hooks
> and armatures. It worked very well and casts were almost always free of
> bubbles.
>
> Obviously concrete is very alkyline and you can't put your bare hands in
the
> mold to get the air bubbles out, and the sand can be real abrasive and
sharp, I
> discovered that when I mixed my first Sakrete up around 1983 to fill a
bath-tub
> sized mold of a standing statue, it was very open in the back so I was
able to
> hand build/pack in the concrete about 3" thick in the face and up the
sides
> with no slump.
> It took 600 pounds of Sakrete and I imagine the first couple of batches
started
> to set while I was packingin the sides, so it worked well. Trouble was I
was
> used to hydrocal and even though both hydrocal and Portland says "Caution
> causes burns" I never got burned by hydrocal and anyway the burn would
come
> from the heat of setting. With the Sakrete I just started mixing a mixing
tray
> with one sack at a time, added the water and thought nothing of packing it
in
> the mold with bare hands. That was, till I guess the next day after I
started
> the finger tips were raw from the sharp sand abrasion, and the rest was a
> chemical burning sensation and it lasted a few days too.
>
> I think after that I used rubber gloves but they didn't last long. I made
about
> 2 dozen of those for a client.
>
>
> << I have never tried those liquid colors. Davis makes some dry pigments,
but
> still the best is the oxides from kremer - look for ones with high tinting
> strength. The only purpose in pursuing these experiments is to maybe >>
>
> Will look into them, the USG guy suggested for hydrocal (and cement)
calling
> this place, blue something, blue mountain pigments maybe- said they have
> pigments made for hydrocal and pigments made for concrete, so I'll have a
bit
> to check soon at least for the buff yellow I want.
>
>
> << Are you going to relaunch your line of reproductions? Maybe we can
> collaborate on something? This foamed magnesium oxysulphachloride cement I
am
> working on will dominate the market. Lightweight, strong and it can take a
> genuine ceramic glaze (apparently, still getting some samples prepared).
>>
>
> Yes, already started, I'm also shortly borrowing back 9 of my castings
from a
> customer I sold them to in 1980 or so, I forgot I sold him that many but
he
> was an avid buyer of my casts back then! Now he is the Mayor of the town
he
> lives in!
>
> By coincidence he sold a '59 Buick to a friend who happens to live not 40
miles
> from me, and the fellow is going to go pick up his Buick in a week or two
and
> agreed to transport the 9 casts back with him, I'll remold them and get
them
> back to him.
> I no longer have the originals of those 9 pieces, so it will be real nice
to
> have them back to remold. With those and what I have right now, I should
have
> about 25 designs.
>
> One of them is a large Neptune keystone, as I remember it took a 5 gallon
pail
> or more to fill the mold with hydrocal, another is a cherub, a corbel, a
female
> keystone, a cornice lion from Columbia College of Pharmacy and a few
others.
> I might be open to looking into a collaboration idea of some kind, right
now
> though I am trying to get the work space workable this fall, get these 9
casts
> and the rest I have molded this fall/winter and cast up some inventory.
Trouble
> with concrete it it has to sit maybe 12 hours in the mold
> which means I'll need to make 2-3 of every mold, then it has to cure for a
week
> in plastic, and then it should cure for 30 days before being stained,
finished
> with whatever or sealed. So I'm guessing I need a lead time of 5 weeks
before I
> could ship a casting just poured today.
>
> I won't be making all my pieces of cement, the little wall plaques and
bookends
> will be hydrocal, it will be the larger stuff like the keystones that get
the
> concrete.
>
> Another issue to is I'll be doing this in my basement, so I kind of want
to
> avoid using nasty stuff down there that has long chemical names you can't
> pronounce if you know what I mean :)
>
>
>
>
>
>
>
>
>
Gary Waller
>
> Sorry the post got launched before it was complete:
here is that ebay item
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3836080384&indexURL=2&photoDisplayType=2#ebayphotohosting
I was going to say that the mark of a mason is that they never use their
hands to handle the plaster or concrete - gauging trowel, bucket trowel,
bucket scoop - but never the hands.
I am working on a pumping system now, to pump the batches into molds.
Don't worry for me about handling those weird chemicals - they are
completely safe. The kiln and glazes is a whole different matter.
Dan S
comments:
GIVE UP this idea of richer = stronger concrete. Pebble mix stronger
than sand mix as well.
If you have to spend so dam much on shipping it's time you get in your
Olds and just drive to where they have the Hcal and wht portland. Get
800 lbs or so and you're way ahead of the game. That's just 3
mothers-in-law.
Dan
----------
In article <20040814214153...@mb-m24.aol.com>,
lostnew...@aol.comcomnet (Lostnewyorkcity) wrote:
>
>
> X-No-Archive: Yes
>
>
> << [Sandblasting with quartz (ailica) sand has been illegal in most places for
> a while now, due to the danger of rapid-onset silicosis. If you look at the
> bag, there should be a warning about this on it. Here's a short article on
> the subject from the CDC: http://www.cdc.gov/niosh/92-102.html ] >>
>
> Thanks Andrew, I did read that article and it is of concern, though there are
> extenuating circumstances with those cases cited there.
>
> I couldn't help notice in the case details that the workers involved either
had
> improper, substandard or broken equipment. It mentioned one who sandblasted
for
> 6 hours a day and then took off his mask and hand shovelled the used sand into
> a hopper for the next 2 hours!
>
> Another had a respirator but gee it wasn't connected to an air tank- go
figure!
> Another case mentioned how the dust collection hopper simply emptied out on
the
> FLOOR to clean it out.
>
> It seemed in every case cited there, the afflicted workers were sandblasting
> fulltime 40 hours a week with substandard, broken or no respirators and poor
> dust collection systems, I can't help think no matter WHAT they used for this
> sandblasting- glass beads, walnut hulls or whatever- the end results would
have
> been the same due to the sheer amount of crap they were breathing in 40 hours
a
> week!
>
> Re color tinting concrete:
>
> << That's something else to experiment with. You get brighter colors if you
> start with white Portland cement - it avoids that gray-green tinge usually
> characteristic of concrete. There are also colors that can be used on the
> surface after unmolding. ] >>
>
>
> Yeah I know, *IF* you can even get white Portland, no one around here carries
> it and for stuff that goes for <$5 a bag most don't seem real keen on special
> ordering it either.
>
> The concrete test piece I cast last Saturday is almost the same color I tint
my
> hydrocal- a dark grey, off how even with 2x as much white sand to that grey
> Portland, it still comes out grey.
>
> Andrew, I need some leads on 2 concrete colors- yellow and red, currently I
use
> black powdered lime proof color made by Rainbow I think... to tint hydrocal,
> only takes a pinch to a bucket.
> I know in the past experiments with colors that adding red in sufficient
> quantity to color hydrocal brick red would prevent it from even hardening!
> I am assuming this is also the case with concrete and that the color may
weaken
> it a little as well?
>
> I think a tint and then a stain wash after demolding is what I'm after. I use
a
> red paint dry brushed on my dry casts followed by a thinned black wash to tone
> down the "newness" of the paint and give it an aged dirty look, but I'd like
to
> get away from paints to get that red, so if I can tint the concrete red I can
> apply a thiined out black stain/concrete color of some kind over it forthe
> same aging reason.
>
> Heres an example of the red I want to get:
>
> http://www.lostnewyorkcity.com/sculpturephotos/Plate-59-s.html
>
>
> I also need a yellow color like this, it has a little orange tint to it but
not
> much:
>
> http://www.lostnewyorkcity.com/sculpturephotos/Plate-69-s.html
>
> I have base paints that are pretty cose to both.
>
>
>
brandon...@gmail.com
Thanks,
Brandon Roth