Rainbow Ridge

Answers to Common Questions




Please feel free to email rainbowridgekits@aol.com or phone 619-561-0643 with any comments or additional questions!

What is Precision Board?


Precision Board is a high density, closed cell, urethane product manufactured by Coastal Enterprises in Orange,
California. Because it does not absorb moisture, and will not rot or deteriorate, it is perfect for structures and
accessories in outdoor garden railways.


Precision Board has no grain, hence it has no beam strength. ½" material is suggested for projects up to 24" long. ¾" material is recommended for projects over that, up to 48". Braces, gussets and other supports should be part of your design. We suggest using no less than 18# density material for projects where texture and grain are important. Use 20# density where sharp edges, corners and details are critical.

What tools can you use on Precision Board?


Any tools that are used on wood can be used to fabricate Precision Board. We use table saws, band saws, routers, etc.


Brushing with a wire brush enhances our wood patterns by adding “grain” and texture. Dremels, dental tools, etc. can
be used for knot or worm holes, board ends and nail holes. Most stone and block patterns come to life with texture
added with Dremels, chisels, craft knives, dental tools, etc. Remove all dust from texturing before proceeding.

Is the dust from Precision Board toxic?


Even though Precision Board is a non-toxic material, you may want to wear a standard particulate dust mask.
Protective eyewear is always suggested.

What glues are recommended for Precision Board?


We have the best success using Gorilla Polyurethane Glue for raw Precision Board joints. Non-foaming glues are easier to use, but do not form the strong bonds needed for lasting strength. We miter all corners. Apply glue sparingly
in flat continuous beads, keeping to inside edge of corner. Spray with a fine mist of water to insure curing. Stainless
steel pins can hold corners temporarily. Either clamp or shrink wrap pieces together while glue sets up. Excess glue
can be cleaned off with acetone before it cures. Coastal Enterprises has recently approved the use of quick setting
glue, in gel form only, with the requirements that it be applied in a continuous bead and the joints be clamped during
cure time. Crazy Glue type products can also be used to attach small pieces of trim that will be primed as part of the
structure. Metal fasteners, such as screws or brads, are not recommended due to expansion and contraction of the
various materials.


Once the PB has been primed, non-foaming glues can be used for final assembly. We prefer clear Silicone, but
products such as Titebond III Wood Glue and gel type Crazy Glue work fine for attaching small trim and detail. To
attach roofs, metal panels, etc., silicone is best because it allows for the expansion and contraction of different


Are there special instructions for priming and painting your projects?


It is critical that you apply equal coats of primer, paint and sealer to all surfaces, both inside and out. This prevents
any possible warping that might be caused by the tension applied to the surface as these coatings dry.

Why should the material be primed with our special primer?


Precision Board’s only known enemy is the UV ray. Priming with a high density urethane compatible primer that
specifically provides UV protection is critical to the longevity of your project. Many skip this step in deference to
added cost and time. Considering the effort you will invest in your creation, why take a chance and ignore the number
one mandate of the manufacturer? Primer also ensures paint adhesion. We offer the primer made by Coastal
Enterprises specifically for Precision Board in 4 and 8 oz. cans. It is included in all of our kits.

What paints can you use on Precision Board?


Any exterior paint can be used. We use the acrylics such as Americana, Delta Ceramcoat and Apple Barrel which are
sold in all craft stores. There is a tremendous array of colors available in convenient 2 oz. bottles.

What product is used to "grout" brick and stone joints?


If you are grouting your project (brick, block, etc. patterns), first be sure the paint is completely dry, 2 or 3 days is
best to ensure curing of the paint. Then grout with non-sanded tile grout available at most home improvement
stores. Gently remove excess grout with a soft sponge, being careful to avoid damage to the paint.

Should you apply a sealer to your projects after painting them?


After all paint and grout have dried, seal all surfaces with a UV resistant, clear, matte finish sealer such as that made
by Krylon available at many craft stores.  The primer protects the Precision Board and the sealer will extend the life of the paint.