# durham rockhard waterputty



## mommacatx3 (Oct 5, 2011)

hi
thanks to everyone for their help
i wanted to pass this on
i dont know if yall heard of this product
but its really great for props and alot less messy than
great stuff easy to mix and dries super hard found it at lowes or homedepot


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## Copchick (Apr 10, 2012)

Is this it? http://www.lowes.com/pd_41341-1789-DRHWP4_0__?productId=3143343










I'll probably try it. Thanks, mommacat.


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## Bone Dancer (Oct 7, 2005)

The reviews are nothing but good for this and the price seems ok too.


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## Lightman (Aug 25, 2014)

My Dad used this for many many years and it works great on wood. I too have it in my shop, but I haven't tried it on foam yet. Our local Home Depot also has it on their shelves.


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## drevilstein (Sep 17, 2013)

I've used it for wood repair, never tried on a prop.


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## drevilstein (Sep 17, 2013)

what applications have you used this for props, if you don't mind me asking?


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## mommacatx3 (Oct 5, 2011)

hi cop chick
yes thats it ive used it for standing props with shoes boots etc just pour it and stick
pvc pipe in it you might have to hold the pvc until it sets which is fast


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## mommacatx3 (Oct 5, 2011)

hi dr evilstein
ive used this on standing props with shoes and pvc mix pour into shoe
and stick pipe in you might have to hold a little bit but it sets pretty fast


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## mommacatx3 (Oct 5, 2011)

hi lightman
i havent tried it on foam either let me know if it works i used it with mostly pvc


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## mommacatx3 (Oct 5, 2011)

hi everyone
ok it does pay to read the back lol
yes it can be molded sanded and water based painted
and its a lot cheaper than great stuff


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## Haunted Bayou (Feb 16, 2007)

So, how heavy is it when it has filled up a shoe? Is it heavy enough to keep a life-size prop standing?


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## Lightman (Aug 25, 2014)

mommacatx3 said:


> hi lightman
> i havent tried it on foam either let me know if it works i used it with mostly pvc


Running EPS foam test now with 5 versions including patching, filling, adhesion, smooth surface, and blob (no foam).

I will post results soon...


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## Lightman (Aug 25, 2014)

*Durham Rock Hard Water Putty - As Foam filler*

I ran a few tests to see how well Durham Rock Hard Water Putty would stand up as a foam filler. After running divot patch, rough surface filler, smooth surface filler and adhesion tests, here are the results....

Results: Using this material on foam has mixed results, some positive and some negative. Since it dries so hard and is not flexible, it cracks easily on foam once cured. Its adhesion characteristics with EPS foam are virtually non existent. It doesn't stick well to the white beads. It does however work well when the material is forced around mechanical anchor points such as porous openings or it surrounds a white bead....then it holds (not sticks) well.

As a filler, it does well to plug the divot, but it most likely will pop out unless mechanically bonded to the beads or an artificial anchor point like a screw. The edges of the crack or divot will most likely separate from the foam if it is flexed in any way.










Background (EDIT 1:30pm): Durham Water Putty is a gypsum based material and has similar traits as plaster products like Hydrocal or Plaster of Paris. It apparently cures via a mild exothermic reaction triggered by addition of water where most likely the molecules combine with water to release heat as they form gypsum crystal structures (theory). Working time is about 5 min or so and it continues to thicken as you work it. It dries (cures) very hard and is non flexible, but sandable. It is used typically to cast molds as well as fill holes in wood, brick, plaster, and other porous materials. It retains paints very well. Durham is used as an additive to help make plaster castings stronger. The Durham website is down for repairs so I cant get more detailed info on its composition. I gathered my info from various sources on the internet.

Post Note: It appears to be water soluble after initial drying (curing). I ground some dried/cured material up, added water and was able to re-create the putty. The 2nd gen cured material exhibits the same characteristics as first gen material. I also cured a 1st gen set in a sealed plastic bag (no air) that got mildly warm, and set up nicely proving an exothermic reaction is taking place.

Process:

I mixed up a batch of Durham Rock Hard Water Putty (Durham) using a little water and stirred till it created a thick paste. See Cup below...










I then filled the divot (see above) with the paste using a tongue depressor and scraped the surface smooth. After 5 hours of cure time, the patch was tested by flexing foam where patch popped out.

Here you can see the anatomy of the patch. The Durham was hard as a rock and conformed to the shape of the beads... but it let go with only the mechanical structure of the material around bead to hold it in place. There is no direct adhesion to the bead surface itself.










I also did a surface test with both smooth foam and roughed up foam (using rasp). I then thinly coated the surfaces and smooth out Durham to let cure for 5 hours. Both surface cracked upon any flexing as well as the chips flaked off the surface....again, no adhesion.

Smooth surface results:









Rough surface results....









I then spread some Durham on a smooth foam piece and pressed another smooth foam piece on top. I let it cure an hour before handling. The bond let go with very little force. No adhesion (seems to be a theme here).

The blob cured 5 hours and is rock hard. This proves that a large amount of Durham will hold together nicely and can be used for molding or some minor sculpting before it cures. The divot patch proves this true also.

Conclusion: Durham Rock Hard Water Putty is a very strong and durable material when it cures, however the lack of adhesion and its brittleness when thin doesn't lend itself to well with flexible foam material. It has its place as a first order filler... but be aware of cracks on edges. Its ability to accept paints may allow the cracks to be covered up with latex paint. It is a great molding material and is a terrific wood, concrete, & plaster filler as its sandable and drillable. But for foam.... Hmmmm.... not the best... IMHO.


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## Bone Dancer (Oct 7, 2005)

Excellent report, I think you covered all the important points for using this material.


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## Lightman (Aug 25, 2014)

Bone Dancer said:


> Excellent report, I think you covered all the important points for using this material.


Thanks Bone Dancer.

I ran some more tests and updated the earlier post. Take a look at the Background section.


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## bobzilla (Nov 13, 2008)

Wow, Brian!
Thanks for taking the time to share all your findings!
I'm loving your mad scientist experiments! :jol:


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## mommacatx3 (Oct 5, 2011)

hi lightman
thanx for the info and great tutorial def not foam friendly thats good to know 
but its 3 cups powder to 1 cup water thats what i use


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## Lightman (Aug 25, 2014)

mommacatx3 said:


> hi lightman
> thanx for the info and great tutorial def not foam friendly thats good to know
> but its 3 cups powder to 1 cup water thats what i use


You are welcome.

Funny story... no sooner did I post my report when I had a foam project that required a divot filler. The hole was pretty much a puncture and went into foam 1/2". I decided to create an internal rim under the surface and fill it with Durham water putty as I needed it to set up fast (20 min). The rim provided a mechanical ledge that would hold in the plug. The foam was thick and wouldn't flex. It worked great! I was able to paint in 20 minutes.

So you see, all these fillers do have their place....depending on the project and its final usage. None of them should be dismissed. Just understand the fillers composition and limitations then go for it!

Have fun!


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## Lightman (Aug 25, 2014)

bobzilla said:


> Wow, Brian!
> Thanks for taking the time to share all your findings!
> I'm loving your mad scientist experiments! :jol:


Hey Bob...you're welcome.

Recently I've been getting into working with foam more and more...sculpting, gluing...and those kinds of things. I always want to know as much about the materials I use so that I can choose them wisely.

Regarding the mad scientist experiments...."Brooo... ha...ha!" (Mad scientist laugh)....I love experimenting with new products. Soon I will post a project I am working on for a friend of mine's halloween haunt (no its not Steve...LOL).


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