Niels from Michigan asks: "What is the difference (chemically) between Durham's and Plaster of Paris? How are the *physical* properties different?"

Niels – Durham's Water Putty is a plaster based compound, however it includes other materials that impart the following characteristics:

• It contains a material to increase the hardness and better bind the product together. This also imparts a smoother and almost "glazed" surface and increases the ability to adhere to surfaces.

• It contains a material to inprove the smoothness of the mixture, improving the surface smoothness characteristics and help it pick up more detail in casting and molding operations.

• It contains a material that slightly colors it to its light yellow color.

Our formulation is a trade secret, but in general, Durham's makes an excellent repair and casting medium because it provides a very smooth, strong, and stable result that is easily workable when wet, does not shrink, adheres well in all sorts of voids, and is able to reliably replicate detailed surfaces.

Durham's doesn't really expire, you just need to be sure that the material is kept dry and sealed in it's can. A very old can may loose some of it's strength. It will still mix fine with the water and it should still be useable for most repairs. If it has gotten hard chunks in it, discard it, since it has somehow gotten damp. If it is still "powdery" it is still OK.

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A reader asked about using my Water Putty on the edges of medium-density fiberboard (MDF) to seal it for painting latter on.

While Durham's Water Putty will fill holes and voids in all kinds of materials, including MDF, it is really not meant to be a sealer and should not be applied in a thin layer over the top surface of a board.  It's meant to be applied "into" a void rather than laid over the top of a surface.

I'm not really sure what you mean by "sealing it for painting" but it sound like that means just applying a layer over the edge of the board.  If that is the case, then I'd say that this is not a good application for our product.

Judy from South Carolina asks: "I'll be using Rock Hard to patch a hole in gray painted cedar siding created by a woodpecker. I would like to add a gray tint in with the water while mixing the Rock Hard. Would the tint at any paint store work?"

Judy –  Durham's can be colored by adding a water-based coloring agent to the putty when it is mixed.  If you want a gray color, I would add a black pigment to it.  I'd suggest a dry powder pigment such as you might find in an art supply store.

Simply coloring the putty will not provide the protection from moisture that it should have, and it should still be painted to protect it from absorbing moisture.  Durham's is not waterproof and when used outdoors, it should be kept painted.

Durham's can be drilled and sawed, but usually does not hold up well to routing. There is too much stress, and the material will usually break under the sort of scraping motion that a router can produce.

Garry from California writes: "Can i use Durham's Water Putty on my rotted window still? I have two separate areas on my sill that need repair. Depth is one and a half inches by seven inches long by one inch wide."

Yes, Garry, you can use Durham's Water Putty outdoors. Our material will withstand the weather when used outdoors, but it must be kept painted.

Water putty is not waterproof, and if it is exposed to moisture, that moisture will be absorbed by the putty and the paint can peel from damp putty patches. If you see any peeling of the paint on a putty patch, you need to find the source of the moisture and correct it so that the moisture is not getting to the putty.

Be sure not to spread the putty in a thin layer over a flat surface, since the putty is intended to be put INTO holes or cracks or voids and not just applied over the surface of a board. When the putty is put over the flat surface of a board, it can come loose when the board expands and contracts during changes in the weather.

If you have a very deep void that you are filling (such as from rot or something) fill it in about 1/4 inch layers, allowing it to dry overnight between layers.  That way, the moisture will have a chance to dry out well between applications, and the patched area will be better prepared and have a lower moisture content when you paint it.

B.L. from California asks: "Could you tell me if DRHWP will adhere to the outside of a plastic container such as an emptied plastic mustard jar and lid with a thin coat? I also want to paint it after it dries."

B.L. – Durham's would not stick well to the outside of the plastic container since if there was any flexing of the pliable plastic of the container, my putty would come off.  If the entire container is covered with a layer of Water Putty say, a quarter of an inch thick, it would support itself and it wouldn't make much difference whether it stayed attached to the plastic, but if you just want to put some putty on the plastic, it would come off when the plastic showed any movement or flexing.

Durham's may be used out doors, but it is not a waterproof material and will absorb moisture even after it is dried completely. It must be kept painted and sealed from moisture, but we do NOT recommend it for repairs on decks or porch floors. These areas are just too susceptible to moisture to be adequately protected from moisture by panting.  Water will be absorbed into the boards from between the boards or from underneath the deck.  The water putty will absorb moisture and if the painted putty patches get damp, it will cause the paint to peel from the putty. For this reason we don't recommend it for repairs to decks or porch floors.

Please keep Durham's in mind for some of your other repairs.

Durham's Water Putty can be used outdoors, but it is not a water proof material. It must be protected from moisture by painting, and must be used where moisture cannot get at it from the back side.

We would not recommend using it to repair the retaining wall.  This area is just much too wet for Durham's to work well. The retaining wall is in contact with the ground and will absorb moisture from the ground. The putty patches would get damp and the paint would peel from them.

Please keep Durham's in mind for some of your other repairs.

I'm sorry, but my Water Putty is not intended to be a cure for leaking concrete foundations and other water leakage areas. It is not waterproof and doesn't work well on leaking basement walls, cracks in concrete pools, or fountains where there is constant hydraulic pressure. There are several other products specifically designed for this purpose that will work better for you.  Check at your local home center, lumber, or hardware store. My Water Putty can be used with concrete, but it is intended for cosmetic repairs,and not structural sorts of repairs.

— Rocky

I recommend a construction adhesive – one that says it works for attaching plaster to surfaces. Be sure your "Water Putty" objects are thoroughly dried before putting them up. If your castings are pretty thick, I'd give them several days for all the moisture to clear out. If you're impatient, like me, you can speed this up by putting them in a low temperature oven (about 150 degrees) for a couple of hours. This drives most of the moisture out and don't worry, my Water Putty will not give off any fumes or anything. Please be careful when you remove your creations from the oven – they will be hot. Let them cool thoroughly before you handle them.

— Rocky

I've never seen a problem with applying fiberglass over our Durham's Rock Hard Water putty.  Just be sure that it's good and dried before proceeding with the fiberglass.

– Rocky

Durham's Water Putty can be drilled and sawed, but usually does not hold up well to routing.  There is too much stress, and the material will usually break under the sort of scraping motion that a router can produce.

Start by going to our "Creative" page to check out "Examples" and download my free 16-page booklet of "Adventures in Water Putty."

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