"Answers to my Frequently Asked Questions."

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 improve 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.

George asks: When did your product first come into existence? I remember using it in the 1940′s in Brooklyn, NY. I still use only Durham’s because it still looks like it comes in the same container. Nice to see a product that has continuity and longevity. No frills, just a good product.

George, it’s great to hear from our long time users, and you certainly qualify!  We started making our Rock Hard Water Putty in 1932. To learn more about how the Donald Durham Company got started, check out our history page.

Durham’s is not intended for use in high temp areas, especially not in fireplace repairs and the like where flames or heat is high enough to start a fire.  It doesn’t burn, but it will break down and crack after exposure to high heat and that would leave an unprotected area where fire could get to the surfaces below the putty.

We recommend not using Durham’s water putty for this kind of repair.

Joy asks, “We are a school trying to repair a plastic bouncy toy. Can you tell me if your product adheres to plastic. We have used it for other surfaces, but what about plastic?”

Joy, great question! Unfortunately, Durham’s will not work for the repair you mentioned. It will not respond well to any flexing and stretching of the subsurface and will not adhere in the patches. Maybe an epoxy material or silicone repair material may be a good choice to fix the plastic. Good luck!

Robert asks, “I have a hole in a foundation and on occasions water stands next to foundation and seeps into building. Hole is about 2 inches in diameter and about the same depth. Will Durham’s work to plug the hole?”

Robert, great question. Unfortunately, Durham’s is NOT a water proof material and is not the right product to fix the sort of hole that you describe. I believe there are concrete-based patching materials that would be appropriate. Check with your local hardware store. I’ve used a hydrolic cement stop leak material to take care of pinhole-sized water leaks and it seems to be very effective. I’m sure a material similar to this would take care of your leak. Good luck to you!

Katy asks: “Just wondering, after the putty has dried and hardened, let’s say over several years, is there any way to remove it short of sanding/drilling/jackhammers? Thank you!”

Katy — removing can be a little difficult. Getting the putty wet and letting it absorb some moisture will not make it soft, but may help in getting it out. You’ll need to break it up or dig it out or, if its not too thick, sand it out. It needs to be removed by mechanical means. I’ve had pretty good luck using a drill down through the middle of the patch and putting a screw or nail in and prying on it to break it loose or break the putty into smaller pieces.

Bob askes: “I am building a military diorama model and need to cover a small area 10″X14″ with something to simulate earth. It will be applied to plywood and wood contour forms and after hardening will be painted and landscape materials attached. Will your product work for this?”

Bob — Yes, Durham’s is often used for this type of effect. It can be spread over the underlying materials and textured, using a piece of damp terrycloth, a sponge or other rough material. You can add more putty if needed. If you want, you can help anchor the putty by putting in some screws in the wood with the heads sticking up and spread the putty all around them, but that’s only necessary if the item is going to get some rough handling. You can embed stones in it to simulate a rocky outcropping. Good luck!

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 lose 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.

I’m glad you asked. Wearing one of my Rock Hard Rocky “Putty Duds” will let everyone know that you’re a person of exquisite taste and refinement. Just click on this Putty Duds link and order your t-shirts today.

David asks: When I mix a portion of Water Putty using the proportions three parts putty to one part water (by volume, as I assume that’s the way you would specify it), I have to stir it for thirty to forty-five minutes before it attains a consistency that can be worked with. The tips for working with it always caution you to work quickly because it hardens so fast. Are they joking?

David — Our newer containers (since about 2006) specify mixing it by weight, since the amount actually varies significantly if done by volume…Putty can be very “fluffy” straight out of the container – and when its “fluffy” there is a different amount than when it is “settled” in the can.  This is the same reason that when baking, measurements for sifted flour may specify packing it into the measuring cup when measuring. Our can instructions read “Pour dry putty into a clean dish and add water little by little, mixing as water is added until desired consistency is reached (about 3 parts powder to 1 part water by weight).”  The water putty is a quite forgiving material and the proportions are not critical, as long as a paste-like consistency is achieved.  You may want it thicker in a vertical application to prevent sagging, or much thinner when casting a figurine.  When mixed to a thick consistency during hot and dry weather, the working time can be rather short, especially if you need to climb a ladder or move to a different location from the mixing area… and of course, everyone’s impression of what “short” means is different!

Brent from Florida wants to use Durham’s Water Putty to repair honeybee frames and wants to know if it is toxic to bees. 

Our material does not contain any toxic ingredients… of course, that toxicity is in regard to human beings… and it has never caused any problems to pets like dogs and cats who have licked or eaten it. Even snakes… but, not being a bee expert, I don’t think I can speak exactly to the point.

I have been here answering questions for nearly 35 years, and have never heard of our product being a problem for bees or had any reports of bees getting ill from contact with Durham’s. There are, however a couple of things to keep in mind. It is not a waterproof material and will absorb liquid sorts of materials. I guess a mold could develop on it, but I imagine that could happen on wood as well.

The ingredients in water putty are mostly derived from minerals, like limestone and a plant based starch binder. We’ve used the same formula for about 80 years, so it doesn’t contain anything that wasn’t around in 1932!

It contains no Volitile Organic Compounds.

Chris asks: I used your water putty to repair/fill a few sections of my exterior window shutters which had some dry rot. I have two questions.

  1.  How long does it take for a large section(3″ x 2″ x 1″) to fully dry for sanding and painting? (Currently, it has been 3 days and the color of the putty area is a dark beige.)
  2. Once dry and sanded, what is the best coating(primer,etc) to insure water resistance? Should I cover the water putty area with an epoxy layer? Or just primer and 2-3 coats of a good exterior paint?

Chris – The patches you mention are pretty large, and more importantly, pretty deep.  The top quarter inch will dry pretty quickly – overnight, but if the putty is applied in one thick application, it may take considerably longer for it to dry thoroughly to the bottom.  Three days seems like it should be an adequate tme frame and sometimes, especially on thick patches, the color does not get uniformly  light.  In the future, if you have a deep fill, I’d usuallyl put it in about a quarter of an inch at a time, letting it dry overnight between applications.  That way it will be good and dry all the way to the bottom.  In this case, and since this is an area where there has been some rot, I’d seal the water putty patches with a coating of Gorilla Glue before painting.  The Gorilla glue is paintable and will provide a waterproof surface for the paint layer, and if the putty should somehow happen to get damp underneath, the coating of Gorilla Glue will help keep the moisture from getting to the paint layer and causing peeling. Don’t wet the surface before putting the Glue on, just spread a thin layer over the patch and let it dry and then paint.

Brian asks: I filled a 2″ x 2″ x 2″ spot with water putty. Can I nail through it without breaking or cracking the putty?

Brian – Sorry, you can’t nail into Durham’s – Its hard and a little brittle and will crack under that sort of attack. I usually drill through the Durham’s and then let the nail embed into the wood beneath the patch.

Karen asks: “My hardwood floors were put down while the wood was still green, now that it has dried out, I have cracks between the boards. Can I use water-based stain instead of water to mix the putty so the cracks will match the rest of the hardwood floors? What about when I put the poly on the floor?”

I’m sorry, Karen, but Durhams will not be the same when mixed with the stain.  It adds a whole bunch of stuff that is not in the putty and will not get hard or be durable. Patching between floor boards is a big problem. If there is any movement, water putty can come loose, and floors need some room between boards for expansion and contraction. Filling the floor solid could cause it to buckle. You almost need some material that will move slightly with the expansion and contraction… and that is not something that Durham’s can do. We have not seen very good  results in filling these cracks with Durham’s.

In response to the Polyurethene question – our material can be finished with a polyurethene finish.

Bob asks, “Our home was built in 1928. For some reason a layer of plaster on a bedroom wall has crumbled. I can see a solid grey-colored wall – I don’t see lath. When the plaster fell off it left me with a hole in a wall and I have to repair it. The hole measures about 24″ x 18″ and it’s about 1/8″ deep. If the wall behind the broken-off plaster was made with some kind of cement, should I apply anything to that wall before using Rock Hard to make the R.H. adhere better? Have use R.H. for small repairs but now I got a big repair job and I want to do it right, thus my question.”

Bob, I don’t think it is necessary to do any sort of treatment to the underlying wall surface – just be sure that it is good and sturdy and not flaky or likely to come off. You’ll want to be sure not to overfill since Durham’s will be a harder surface than the plaster. You are better off to have to add a little more to the patch than work to remove any excess!

Greg asks, “I have recently purchased a three piece slate pool table. Is your product suitable for use as a screw hole filler and seam filler on the pool table slate?”

Greg, our product has been used for this purpose for many years. It expands slightly as it sets up, so you’ll want to be sure that it is level by checking it frequently as it sets up and scraping off any excess. Use a very wide bladed putty knife for this purpose. If you find it a little under-filled, it sticks very well to itself so you can go back and add a little more.

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

Perry asks, “I bought your water putty to use in making a mother mold for some (small size) brush-on silicone molds I am creating. Looking for some detailed How-To’s on using gauze or fiberglass shreds …. or anything about how to prepare a mother-mold. So how do you suggest I should prepare water putty to “trowel” it on to my silicone Glove Molds?”

Perry – I’ve only made a couple of mother molds using Durham’s. I just made small frames with small dimension wood hooked together with duct tape, and lined it with kitchen plastic wrap (so the putty wouldn’t stick to the wood).  I then poured it almost full with water putty and placed the silicone mold into it (with the things I was casting still in the mold) and let it dry around it. After it was dried, I removed the silicone mold, took the framework off the mother mold, and that’s what I used to support it during casting. I didn’t use any gauze or fiberglass reinforcement.

Ted  from North Carolina asks,  ”Can I use Water Putty to make a mold then when cured, coat the inside with cooking spray or Vaseline and use it for a mold to cast parts out of water putty?”

Ted, Durham’s is intended to stick to itself, so that makes having both the mold and the casting medium made out of Water Putty difficult, and releases don’t work very well. We’ve tried lots of releases, and none are really good or release well without being so thick that it distorts the molded object.  The best molds for casting water putty are made out of latex or some other rubber substance.  You can get flexible mold making supplies at a lot of art or craft suppliers. In rubber molds, you don’t need a release for the water putty and it will release as it is turned out of the mold.

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.”

Then head over to our Facebook page.

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