Caenstone
Caenstone when properly executed is every bit as convincing in feel and appearance as it's decorative counterparts "Scagliola" and "Marrezzo". Used entensively in ecclesiastical architecture, it was widely used in the grand old "atmospheric" theatres of the 1920's and 30's, as well as office buildings and residences.
The original formula calls for neat plaster and sand with mineral pigments added to produce the desired color, and mica chips to make it sparkle when hit by light. This was applied over a traditional scratch and brown coat on lath or masonry. On jobs where higher quality was required the same mix was used on all three coats, this would eliminate and difference in color if it got chipped or damaged. In areas where extra strength was required Keenes cement was used instead of plaster. However, Keenes cement changed the formula somewhat since Keenes is white and neat plaster in gray or brown. The proportions of sand to plaster are roughly 3 to 1, a small amount of lime can be added to make the mix more plastic and easier to trowel. The usual process was to apply the scratch coat one-day, brown coat the next day, and finish the third day. As the finish began to set it was sponged, or worked with a wood float to bring the sand to the surface, then as it started to set again it was re-troweled to push the sand back slightly to produce the ashlar finish. Extra care needs to be taken at this point because the more it is troweled the darker it gets. Before the finish sets the lines for the joints can be struck in. After the finish sets the lines for the joints can be struck in. If the grout lines or joints need to be cleaned up after the plaster sets they can be ground down using a wetstone. Another option is to go over the entire surface with a wetstone to expose more of the aggregate to get a greater variation in color.
Another advantage of caenstone since it is plaster is it can be cast in moulds or run en-situ.
The following photos will give a small idea of what can be accomplished with caenstone and where it can be used.
Preparation:
Material should be applied to surfaces that are clean and free of dust, dirt, and oils. If material is being applied to new sheetrock, blue board, or rock lath all joints must be taped using self -adhesive mesh tape, It is best to fill tapered joints with basecoat to level. Mesh tape can either be bedded in wet material or applied to surface after it has dried. Sink all nail or screw heads and cover with small square of mesh tape.
If material is being applied to existing painted plaster surfaces, remove any loose or spauling paint. Surfaces should be clean and free of dust, dirt and oils. Test for calcimine and remove if any is found. Large cracks should be covered with mesh tape.
Extensive "network" or mapline " cracking should be covered with wider mesh tape, available in 36" wide rolls. Loose plaster should be removed and patched with structolite or comparable material or reattached using screws and plaster washers.
Patch any large holes or voids in plaster using structolite or comparable material, level to existing finish surface. Holes may also be patched using sheetrock or other like material. Cut sheetrock as closely as possible to the shape of the hole. Shim the sheetrock as close to existing finished surface as possible. Fill around edges with "Master of Plaster" basecoat allow to dry overnight. If large voids are filled, some minor shrink cracking may occur. Allow to dry completely and refill flush with surface. Tape edge of patch with self-adhesive mesh tape. Make sure tape covers both the patch and the existing plaster surfaces. Skim entire wall and ceiling surfaces, including patch using "Master of Plaster" basecoat.
Application:
Master of Plaster Stone finish is meant to be applied in three coats. First a white basecoat to true the substrate. Second a color basecoat to act as the joint line. Third the stone finish.
Use directly from container. It is not necessary to mix or add water. Material
is best applied using a hawk and standard size 3"x10" Stainless
steel finishing trowel. Master of Plaster basecoat is self leveling. Apply
basecoat to all surfaces as thinly as possible. As material starts to set
(approx. 15-20 minutes) go back over work an trowel as smooth as possible,
(some ridges and trowel marks will remain). Allow to set 3-4 hours, overnight
is recommended.
When basecoat has dried, apply second coat of (colored) basecoat as thinly and smoothly as possible. As material starts to set (approx. 10-15 minutes) Using a small plant mister (spay bottle) lightly spray area with water and smooth removing all trowel marks and blemishes. Since "Master of Plaster" feathers out and blends easily, it is possible to work smaller areas rather than having to do one large area at a time. Just keep the edges wet and it will all blend together. "Master of Plaster" is a very forgiving system. If an area gets too dry, or you did not get all the trowel marks out, just re-wet and trowel until desired effect is achieved.
After the second
basecoat has dried, apply the finish coat slightly thicker than the second
basecoat. The finish coat has a coarser aggregate so it needs to be applied
only slightly heavier to level out. as the finish coat just begins to set,
rub it with a wooden float. This will bring the coarser aggregate to the surface
and cause it to scratch the surface this is the effect you want at this point.
The more scratches the better. As the finish begins to set again, lightly
spray it with a plant mister and re-trowel. As you re-trowel the scratches
will begin to fill in and the coarse aggregate well sink back into the Finnish.
Keep troweling until the desired effect is achieved. It is desirable to have
some of the scratches remain. After the finish coat has dried (approx. 12
hrs.) you can lay out and strike the joint lines. No special tools are needed
to cut the joint lines, you can use anything from a nail to a "church
key"(can opener). The "church key" will give a nice "V"
joint. Use a hard straight edge as a guide when striking joints. Keep lines
straight and true. Some chipping will occur while cutting, this is desirable.
Be careful not to cut through the second basecoat to the white coat. Following
these instructions will produce a realistic ashlar face limestone finish.
However we encourage you to experiment with different treatments. Sponging
with produce a coarse finish. Dragging a whisk broom through it before re-troweling
will add further interest. After it has set you can gently cut some of the
blocks with a toothed stone chisel to leave quarry marks. Always do sample
boards prior to starting a project.
Master of Plaster stone finish comes in tan and yellow however custom colors
can be mixed to match existing stone or stone finishes.
Coverage:
Basecoat white
- 170-220 sq. ft. per 5 gallon bucket
Basecoat joint color - 170-220 sq. ft. per 5 gallon bucket
Finish coat - 140-180 sq. ft. per 5 gallon bucket
$165.00 per container +shipping
Cleanup:
Wash tools with plain water. Wipe dry to prevent rusting.
Storage:
Keep containers tightly closed. After material has been removed, replace cover. To preserve remaining material at the end of a project. Scrape sides of bucket and cover with cellophane or 1 inch of water. Unused material will keep for up to a year following these practices.
Shelf life of unopened material is 2 years. Do not store outside. Keep out of direct sunlight. protect from freezing.
Caution:
Master of Plaster
was designed not to be sanded. This product contains mica. Long term
breathing of large amounts of mica dust may cause lung disease. Do not
sand. Use of safety glasses is recommended.
Keep out of the reach of children.
Liability:
We shall not be liable for incidental and consequential damages, directly or indirectly sustained, nor for any loss caused by application of these goods not in accordance with current printed instructions or for other than intended use. Our liability is expressly limited to replacement of defective goods.
