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  #1  
Old 02-22-2006, 11:06 AM
georkalm georkalm is offline
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Plaster firmer

Does anyone have a solution for making plaster less fragile (adding any chemicals or materials) and more flexible. Or does anyone use a material that is like plaster for relief work (but not resin)?
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  #2  
Old 02-22-2006, 01:43 PM
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Re: Plaster firmer

flexible plaster
hmmmmmmmmmm
interesting concept

harder use hydrocal or cast stone-see your local supplier-they carry different products depending on what sells--I drive 80 miles to davenport as they get materials by barge and rail and have a fresher and better selection than the local folks and at a good'nuff savings to cover the cost of the trip
also-make sure the stuff is fresh---old plaster tends to not set well
and, if your adding a colorant some retard the set or soften it

for tougher add latex to the mix

then viabrate the plaster in the bucket and/or mold to remove most air bubbles
test small batch first

and you can mix in fiberglass strands or burlap,etc.,... for more strength---
long ago, folks added horse hair

what're you trying to cast?

rod
sculptor
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  #3  
Old 02-23-2006, 02:00 AM
georkalm georkalm is offline
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Re: Plaster firmer

Thanks for the reply. I am not casting. I am making plaster reliefs. There is something I love about the look and weight but chipping and breakage is always a threat - I'd love to get the look and feel with less fragility. I have made reliefs that have lasted over 20 years already without show of wear but others have chipped and repair to old plaster is hard. Your idea of latex is a good one - what kind of work do you do?
George
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  #4  
Old 02-23-2006, 03:40 AM
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Merlion Merlion is offline
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Re: Plaster firmer

Quote:
Originally Posted by georkalm
Thanks for the reply. I am not casting. I am making plaster reliefs. There is something I love about the look and weight but chipping and breakage is always a threat - I'd love to get the look and feel with less fragility.
Dry plaster is strong only when it is a solid block. But when it has sharp corners or edges, or when it is thin and slender, it is very weak against chipping and bending.

To strengthen plaster, I use fiberglass mats. I wet the mat with wet plaster and lay them into the plaster cast. They do help to strengthen the plaster relief sculpture.

These mats are the same chopped strand mats we cut into short strips and added to resin to make fiberglass resin sculptures.

Anyway, your enquiry has prompted to make further enquiries with my fiberglass supplier. Apparently they also supply chopped strands, i.e. not in the form of mat. Thus these strands can be mixed into the wet plaster to reinforce it when it dries and hardens.

Last edited by Merlion : 02-23-2006 at 06:15 AM.
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  #5  
Old 02-23-2006, 07:51 AM
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Re: Plaster firmer

That's the misleading thing about USG's specs on hydrocal etc., they chart out things like COMPRESSIVE strength "15,000 psi" or whatever it is compared to say Plaster of Paris at say "1000 psi" looks pretty impressive doesn't it?

But unless you are planning to use the block of hydrocal or Plaster as a "base" for a floor jack for jacking up your car to change a flat tire, the compressive strength is all but worthless a figure. The most common damage is shock damage- sudden impact.

Statues, scuptures and the like are not normally used to support weight, they ARE moved, handled, objects and people move around them frequently and each encounter is an opportunity for a collision. Plaster of Paris, hydrocal, or harder hydrostone will ALL scratch and chip if something bumps up against them like say, a deliveryman's metal hand truck or dolly, someone walking by with a 2x4, and electrician walking by with an armload of metal conduit, bike rider leaning his bike against it.

I actually found cast aluminum like my griffin is not much harder than hydrostone too, you can take an xacto knife or sanding block and put a fair sized bevel on a sharp edge real easy- it almost can be cut that way like hardwood, it also scratches and CAN be broken. I'm not so sure making plaster harder or adding latex is really in the real world going to help much- if something hard bangs up against the sculpture it's going to chip or dent or damage, the trick is to design it so there ARENT many fragile projections that can be snapped off, and/or place it in a location that contact with it is unlikely, or us a material other than plaster/cements.

Last edited by Landseer : 02-23-2006 at 12:10 PM.
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  #6  
Old 05-24-2006, 12:07 AM
syrus syrus is offline
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Re: Plaster firmer

Hello all, I'm just a newbee but I can't find hydrostone or any other casting plaster so I also wanted to find something to make plaster of paris less brittle. While serching on the internet I found someone saying add some DURHUM"S rock hard water putty to the palster. You can buy it at any hardwear store. It's a powder and mix it right in with the plaster. I had some of this stuff lying around at my home and added it to my plaster and boy it works great! Makes it much stronger, less brittle, and I bet if I dropped it would'nt break. I only used about a 1-10 ratio water putty to plaster, But that ratio can be varied to add as much as you want. I would bet you could even cast straight water putty. I just tried it for the first time this morning and will have to experment more. But the 1-10 ratio I used seems to be as hard as anybody would want it..............
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  #7  
Old 05-24-2006, 04:09 AM
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Re: Plaster firmer

Ok, a maybe simple but still worthy is CISAL FIBERS.
To strengthen the mass.

Now, a new high-tech cement has bending capability and incredibly thin wall needed for good resistance. It is called here: DUCTAL.
Really impressive.
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  #8  
Old 05-24-2006, 08:13 PM
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Re: Plaster firmer

Quote:
Originally Posted by syrus
I found someone saying add some DURHUM"S rock hard water putty to the palster. You can buy it at any hardwear store....
Yeah I've used this for patching in the house, it's not cheap for one thing, and the other issue is it takes forever to set and harden up when used, I don't know how it works in plaster, but it didn't seem any harder than hydrocal to me which is quite harder than "plaster" itself anyway.

The water putty is a kind of pale orange color, so unless the cast is going to be painted then the tint might be objectionable. Many of my casts get stained, so a wierd orangy tint in the cast would really mess me up.

Sculpture House has some kind of plaster hardener I remember, never tried it, I think it's bone meal so I am guessing that like sand it would be a filler and most filelrs don't add strength they weaken.
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Old 05-24-2006, 09:05 PM
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Re: Plaster firmer

It would be more useful if anyone can explain what materials or mixtures are Hydrocal, Durham's water putty, and Ductal. I think these are trade names which generally have no meaning to sculptors from other countries.
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  #10  
Old 05-24-2006, 09:53 PM
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Re: Plaster firmer

http://gypsumsolutions.com/search_de....asp?DocId=580
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  #11  
Old 05-24-2006, 09:57 PM
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Re: Plaster firmer

Quote:
Originally Posted by Merlion
It would be more useful if anyone can explain what materials or mixtures are Hydrocal, Durham's water putty, and Ductal. I think these are trade names which generally have no meaning to sculptors from other countries.
They are all trade names, I don't know what Ductal is but the water putty seemed to me to be little more than colored plaster in a cardboard canister at the hardware store, used for patching walls, holes, filling cracks, it's pretty expensive at about $6 for 4 pounds!


Donald Durham Company -- Makers of Durham's Rock Hard Water Putty ...Home page for The Donald Durham Company. Durham's Rock Hard Water Putty(tm) is a gypsum-based water putty. Use it to repair wood, tile, stone, and plaster.
www.waterputty.com/
What Is Durham's Water PuttyDurham's Rock Hard Water Putty is a gypsum-based filler -- a powder ... For repair jobs, Durham's Water Putty fills voids like holes, cracks, and the like. ...
www.waterputty.com/view.htm


Hirst Arts Casting Page Durhams Water Putty is one of the greatest mixtures available for those that cannot afford more expensive dental products. It is about $5.96 for 4 Pounds of ...
www.hirstarts.com/casting/us.html
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  #12  
Old 05-24-2006, 10:18 PM
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Re: Plaster firmer

http://www.umich.edu/news/?Releases/2005/May05/r050405

bendable concrete

" ECC concrete gives because the specially coated network of fibers veining the cement is allowed to slide within the cement, thus avoiding the inflexibility that causes brittleness and breakage"
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  #13  
Old 05-24-2006, 11:03 PM
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Re: Plaster firmer

other fiber-reinforced concretes in development today. The key is that ECC is engineered, Li said, which means that in addition to reinforcing the concrete with microscale fibers that act as ligaments to bond the concrete more tightly, scientists design the ingredients in the concrete itself to make it more flexible.


Pretty interesting url/info, I am just a bit wary of this "microscale fibers" used, it sounds like it would be real wicked to be working with in any scale- think asbestos and you can see where I'm going.
"micro fibers" is going to be something that is easily respirated, yes, you can wear a mask etc, but unless you wear a clean-room bunny suit you'd have it on your clothes, shoes, the floor etc.
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  #14  
Old 05-24-2006, 11:25 PM
syrus syrus is offline
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Re: Plaster firmer

Hello everyone, Now why wouldn't liquid latex added to plaster make it less brittle? In my mind it makes good sense. But I'm a newbee so.... Has anyone tried liquid latex added to plaster?...................
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  #15  
Old 05-24-2006, 11:53 PM
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Re: Plaster firmer

Quote:
Originally Posted by syrus
Hello everyone, Now why wouldn't liquid latex added to plaster make it less brittle? In my mind it makes good sense. But I'm a newbee so.... Has anyone tried liquid latex added to plaster?...................
It probably would, but with additives there's a number of issues- COST is just one of them- if you have to add say a quart of chemical "X" to harden a pail of plaster and the quart of "X" costs $21.95 plus shipping and the plaster costs you $1.25 for the pailfull, and you are selling the product made from that pailfull for $19.95, well you can see the problem no?

For the most part plaster and the gypsum formulas is used because it IS cheap, but when you start messing with adding surface hardening chemicals, colorants, retarders, fillers, reinforcement and so on, well you begin creating a mighty expensive pail of plaster that can cost more by that point than some other already more durable material- foamed in urethane, epoxy, liquid plastics, resins etc

A lot of additives, colors, retarders, fillers, aggregates etc if they don't weaken the plaster they don't help it any, some can retard the set or change how it "works" others can alter the cast in such a way that the stains you developed for the plaster casts no longer work.

Last edited by Landseer : 05-24-2006 at 11:55 PM.
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  #16  
Old 05-25-2006, 03:24 AM
syrus syrus is offline
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Re: Plaster firmer

Thanks, very good point! Try to keep the cost down is a big priority, (in case one needs it for a special reason, It's nice to know there are other options)and the batch of plaster and water putty is strong enough (I used a very small amount of water putty) to go from the mold to being painted to be put up on the wall. But the Items I'm making need to be shipped and that's a different story all together. Get tossed onto a truck and bounced around for 3-7 days.............


Which comes to another question when having to ship an item. anything to add to plaster to make it weigh less or lighter? ............

Last edited by syrus : 05-25-2006 at 03:35 AM. Reason: Added thought
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Old 05-25-2006, 07:37 AM
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Re: Plaster firmer

Landseer,

<For the most part plaster and the gypsum formulas is used because it IS cheap, but when you start messing with adding surface hardening chemicals, colorants, retarders, fillers, reinforcement and so on, well you begin creating a mighty expensive pail of plaster that can cost more by that point than some other already more durable material- foamed in urethane, epoxy, liquid plastics, resins etc>

I am also like Syrus interested in this. Am interested in plaster possibilities for workabilities, small health risk, and the final finish that can be achieved. Recently read a screed by Chris Pardell on urethane, epoxies, plastics, and resins and from a health standpoint they sound fairly noxious. Allergic sensitizers, headaches, etc.

Cost of the material is not the central issue. Health and final finish are. Cost can be justified to a client witin reason.

Am not casting a final product but using plaster as lightweight medium to do swirling design elements that will be mechanically attached to a base. The base and wall relief should be light enough for a client to fasten to a wall and stay there.

If the qualities of plaster can not be changed or modified - is there another medium that could be used?

Can plaster be aereated like concrete?

Recommend a book that might have more possiblities to explore?


Any suggestions would be welcome.

Carl
www.wsggallery.com
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  #18  
Old 05-25-2006, 08:21 AM
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Re: Plaster firmer

Quote:
Originally Posted by syrus
But the Items I'm making need to be shipped and that's a different story all together. Get tossed onto a truck and bounced around for 3-7 days.............


Which comes to another question when having to ship an item. anything to add to plaster to make it weigh less or lighter? ............
Every piece I make gets shipped, I use DHL and have rarely ever had any breakage, you just need to use a box that is big enough and what I do is put 2" of peanuts on the bottom then a sheet of 1" styrofoam board, lines the 4 sides with more of the styrofoam, put the sculpture in bubble wrap in, fill with either excelsior/newspaper/wadded brown kraft paper, another sheet of styrofoam on top and it's on it's way.
In 18 months or so of shipping multiple boxes out every week, I can only remember a couple of breaks.

If you check the shipper's rate charts, you will find now that the weight isn't so much a big deal, it only costs a couple of bucks more to ship a 40# box than a 30# box coast to coast, where they get you is the zone/distance, the pickup charge, $3 a box, and the residential delivery surcharge $2 a box, so right there is $5 in fees before the box even moves anywhere.
That is why I'm moving to a flat rate shipping change now, I just don't have the time to look up every single inquiry's zip codes, enter the box sizes, weights, origin zip etc etc to quote shipping charges. I have found they rarely vary on a particular sculpture more than $3-$4 whether it's going one state over or all the way to Southern Florida.

You can add fillers to plaster or hollow the casts out, but I have found generally you can't get much weight off scooping some of the plaster back out to hollow it a bit, and any fillers you mix in if they don't weaken the cast they sure don't add any strength.
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Old 05-25-2006, 08:31 AM
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Re: Plaster firmer

Quote:
Originally Posted by tonofelephant

urethane, epoxies, plastics, and resins and from a health standpoint they sound fairly noxious. Allergic sensitizers, headaches, etc.
Yes, there you go- exactly, and add carcinogenic and cost to that. This was one reason I only even made ONE cold cast bronze- it wound up costing me so much in materials that I calculated that for another $100 or less I could have had a foundry cast the piece in REAL bronze.



Quote:
If the qualities of plaster can not be changed or modified - is there another medium that could be used?

Can plaster be aereated like concrete?

Recommend a book that might have more possiblities to explore?
Plaster and it's varieties- hydrostone, hydrocal etc is pretty unique, hydrocal is MUCH stronger than plaster of paris but it also weighs more per cubic foot- about 111#, hydrostone is harder yet. I currently pay near $32 for a 100# bag of it delivered.

Other formulas, like "Vatican Art" from Sculpture House have quartz aggregate and colors, but it only comes in up to 25# boxes and it's now I saw somewhere about $50 a box. I've used it 25 years ago when it was about $9 a box and I thought THAT was expensive. Ive seen some interesting effects done on it, it can be sort of polished to bring out the crystals too, but that's the equiv of $200 for 100# v/s the $32 I pay for hydrocal.

Other materials, there's ceramic slip and clay but you need a kiln...
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  #20  
Old 05-30-2006, 06:34 AM
seaportmold seaportmold is offline
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Re: Plaster firmer

I use screen in hard draw areas
www.seaportmold.com
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  #21  
Old 04-29-2008, 01:21 PM
julia burton julia burton is offline
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Re: Plaster firmer

This may help you a little. I tried putting wood glue (the kind with the cow on it) in place of some of the water when mixing the plaster. It was very hard. I threw it down and it did not break. Although I know of nothing that will make plaster flexable the glue did seem to make it chip resistant in a way that sugests maybe the glue stays a bit flexable. I can't remember exactly how much I used but it was probably about 1 part glue to 5 parts water. I used regular Elmer's wood glue. It was an almond color when dry. An inexpensive possibility.
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  #22  
Old 04-30-2008, 03:56 AM
furby furby is offline
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Re: Plaster firmer

i was told as a student that egg whites make for tough plaster.
and at least they are easy to acquire.
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  #23  
Old 05-01-2008, 10:22 PM
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Re: Plaster firmer

have you tried Ultracal 30? its stronger than hydrocal. You can add a chemical, well acrylic binder called Acryl60, there are binding agents you can get.
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