Technology of plastering columns of various shapes

Plastering columns is a special kind of work where form and function are combined. Columns give character to any space, whether it is in a modern or classical setting. But to achieve a smooth and perfect finish, their irregular shapes—round, square, or even more intricate designs—call for unique techniques.

Plastering columns uses different technologies depending on the shape and end goal. For instance, round columns require careful handling to guarantee the plaster flows smoothly around the curve. To achieve crisp corners and clean edges, precision is required for square or rectangular columns.

This post will examine the various techniques for plastering columns with a range of shapes. You will discover the best practices to guarantee your columns appear polished and professional, from planning to final touches.

Column Shape	Plastering Technique
Round Columns	Apply a thin layer of plaster, using a flexible trowel to follow the curve. Work in small sections and smooth evenly.
Square Columns	Use a straight edge to apply plaster in even strokes. Start from the top, moving down, ensuring straight, clean corners.
Rectangular Columns	Apply plaster using a broad trowel. Focus on keeping edges sharp and surfaces flat.
Complex Columns (Decorative)	Use special molds to maintain intricate details. Apply the plaster carefully, ensuring no loss of the design.

Types and device of columns

From a structural standpoint, these are vertically elongated elements of various shapes that support floor beams or purlins.

• tetrahedral (square or rectangular cross-section);
• elliptical;
• round;
• polyhedral (with six or more faces).

Additionally, there are elements that resemble them in appearance, such as pilaster columns and half-columns. The structural components of the columns, also known as pillars, are a base (foundation), a capital (top), and a trunk.

A pillar can either have an even cross-sectional area the whole way down to the ceiling, or it can have an uneven cross-sectional area that decreases (with a device entasis). Traditional form of entasis: the trunk portion progressively narrows above and takes the form of a cylinder in the lower third of the height.

The ancient Egyptians used flutes, which visually lengthen and thin the trunk. The name means "spoon" or "groove" when translated from French. A smooth conclusion of the groove to zero can be found at the end of longitudinal cuts with a cross-section that is a third of a circle or a semicircle. There are flat belts that resemble ribbons in between the grooves. Fluted columns may have a screw-like form.

Rustication is another style of decoration. Rustovation is an imitation technique that involves folding the trunk from stone blocks or facing with stone plates. Square column edges are occasionally embellished with moldings, which are thin strips with motifs on them that are used to create figures, such as frames. The pillars can be adorned with capitals or bases in addition to the trunk’s design.

The columnar body may be composed of the same materials as the walls, namely concrete, metal, brick, or wood. Consequently, the base material affects certain aspects of plastering.

Preliminary hanging

The hanging operation (derived from the word weight) is used in plastering to produce precise geometric shapes. Regardless of how many there are, the geometric shapes of the columns need to be created with extreme precision because any deviation from the ideal will be immediately apparent against the background of other elements. Everything has to be done precisely: faces, rib lines, flute beginning and end lines, rustication step, column row straightness.

We start by suspending the colonnade from an external column.

1. At the top of the trunk, we install a self-tapping screw (or make a mark), the top of the cap of which is separated from the surface by the thickness of the plaster layer.
2. A plumb line is lowered over the cap.
3. At the bottom, we install a second self-tapping screw along the plumb line so that the cap touches the thread of the weight. If the column is blocked, or there is a hump that cannot be cut down, we adjust the distance of the vertical thread by unscrewing the screws. This increases the thickness of the layer.
4. We tie a thread running over the caps to the exposed screws, taut.
5. We install one or two more screws under the thread, for example, in the middle.
6. We repeat the hanging operation on the other extreme column.
7. We stretch horizontal threads along the screws on the extreme columns along the colonnade, forming an auxiliary vertical plane. (If necessary, you can stretch diagonal threads).
8. Focusing on the auxiliary plane, we set screws or marks on the intermediate columns.
9. After setting the screws on one side (front), we repeat the same procedure, installing screws (marks) on the back side.

If you need to hang a column that has entasis, then first screw in the screw at the bottom of the trunk, where the radius of the trunk is the largest. The height of the cap at the bottom should be equal to the thickness of the plaster. Then, on top of the retractable horizontal element (the length is greater than the difference between the upper and lower radii of the trunk), we hang a weight at such a distance that the plumb line thread touches the lower screw. From the suspension point at the top, we measure the difference in the lengths of the radii. This place will be the top of the head of the second screw or brand.

When the lower radius is 360 mm and the upper radius is 200 mm, for instance, the difference is 160 mm. The upper screw’s head should be 160 mm away from the plumb line thread. We follow the same procedure to obtain the desired point in the middle of the trunk. In the event that the column exhibits double entasis, or tapering towards both ends, the starting point where the trunk’s diameter is largest is used. We use a similar method for hanging half-columns and pilasters.

Make sure that the flutes end on the same horizontal when hanging, and that the edges of each row of rectangular columns are the same width.

Construction of marks

Plaster mortar is applied in piles along the plumb line to create marks. Using the plumb line as a guide, cut off the top. Additionally, the mortar on the pile’s sides is chopped off to create clean marks. Cut pieces of plasterboard can be used in place of mortar.

After putting the template in place, the marks on the round columns will also act as a bottom for pouring the beacon, so the top is chopped off along the horizontal line. Marks are placed in belt lines—that is, multiple rings of marks are made around the trunk—for round trunks plastered along beacons. The length of the rule should be the same as the distance between the rings. From one to 1.5 meters, that is. More rings are created if the room’s height reaches five meters.

A palm-sized cake of mortar is applied to the trunk to create a mark, and its top is then chopped off along the plumb line. Twenty to thirty millimeters separates the marks of columns with a round and polygonal section. Square section pillars are positioned closer to the edges because markings are required for accurate rule installation.

Beacons

Beacons for walls are not the same as guides for plastering pillars. Only round and semicircular columns use beacons; other columns do not. Additionally, beacons are required for plastering pilasters. In this instance, beacons resemble belts and cross the trunk. In order to create a beacon, a ring template is required.

Use a board shield to create a ring template. Draw a circle the diameter of the column on a shield that has been knocked down from 20–30 mm boards, accounting for the plaster layer. The semicircles on the shield are cut out and removed after it is sawed in half, or the boards are separated. The template is folded in half after the cut line has been cleaned. Mortar beacons are created by assembling the split ring that results, connecting it with tenons and grooves.

Two (or more) ring templates with varying diameters are made for entasis. To stop the gypsum from sticking, lime mortar is applied to the inner surface of the template.

The templates act as a kind of formwork for the surrounding beacon. Nails are hammered into the trunk all the way around or marks are made in order to install and secure the template. After the template has been positioned on the trunk, gypsum is used to secure it from below. The rings are gently knocked off after the gypsum plaster mortar is thrown from above into the space created by the trunk and the ring beacon. The beacons’ bodies have leveled and sealed pores.

Beacons can also be made in two other ways. For instance, if there are a lot of columns, a mold for the beacon half rings is created, and the necessary quantity of rings is cast. The rings are then split into halves and mortared to the trunk.

Plastering round columns

There are two methods for leveling a surface with plaster:

• by beacons (or by hand);
• by pulling.

Half of the surface is covered with semicircular templates that are used to pull out straight columns. In this instance, the marks are hung with two rules (or guide rails on opposing sides). Running the template alternating on both sides over the entire surface ensures that the guide installation is accurate before pulling.

Determine which guide is not vertical and adjust its position if the template fits on one side but hangs between the guides on the other (this can be done by wiring the template).

1. Plastering of columns begins with a spray, which is applied to the entire surface.
2. After it dries, a primer solution is applied to the entire height between the two guides. Read more about choosing a primer on our website.
3. Having installed the template from below, it is led upward, the cut mixture is removed with a spatula.
4. The template is used several times until a flat surface is formed.
5. Then the second half is plastered.

Plastering of tetrahedral columns

Columns with square cross sections are the easiest to plaster.

The geometric maintenance of the following parameters is required:

• plane of faces;
• right angle between adjacent faces;
• verticality of faces.

Plastering guidelines are rules affixed to both cheeks with screws (or even wooden slats with marks or cords stretched appropriately for hanging). Plastering walls with beacons is comparable to the plastering process. Using a short rule or half-trowel, the applied primer is leveled along the edges of the long rules or slats that protrude. It is rubbed off the applied cover.

The guide rules are taken down, applied to the other face, and plastered after one face has been plastered. Allow the solution to air dry. The two remaining faces are then similarly plastered in pairs. Rubbing the whiskers is the final step.

Columns with a curved contour

There are multiple rules for placing entasis elements in beacons. Ring beacons are used in conjunction with a straight-line rule to complete the cylindrical portion. A pattern rule is applied to the tapering portion of the trunk. The entire column’s body is instantly treated with the solution, and after it has been leveled, the rule is moved around the trunk. Once a level surface has been achieved after a few passes, let the solution to settle, take out the beacons, and then fill the groove with the solution. A concave trowel is used for grouting and covering.

Plastering polyhedral columns

Here, a template is used to help with the plastering of the columns. What matters most is that the polyhedral column template is created with the equal width of the edges in mind. Make sure the self-tapping screw marks are strictly along the edge’s longitudinal axis when hanging, and that the edges are vertical. On the marks of two opposing faces, the guide rails are put in place. Run a template the full height to ensure the rails are in the correct position before pulling. Vertical deviations of the rails are allowed, but they must not exceed 5 mm over their whole length or 1 mm for every meter of height.

Finishing the flutes

Usually, round-shaped trunks are decorated with grooves; faceted trunks are used less frequently. Flutes can encircle the trunk or run along the vertical axis.

Flute formation can be done in two ways:

• cutting;
• by pulling.

To cut out the previously applied and rubbed layer of tumbled mortar, a specially designed template with a metal border is utilized. The more common approach is the second one, pulling. When removing the mortar, a semicircle-shaped template is used. The flutes’ smooth, semicircular exits at the barrel’s ends are created by hand.

Straight on tetrahedral columns

Making grooves on rectangular columns is the easiest method. The contours of the intended belt-equipped groove profile are drawn on a flat, planed board to create a template. The drawing then shows that a figured edge is cut out. The board is secured on both sides by thin steel sheets, and the runners are fastened to the bars (skid) by self-tapping screws (refer to the drawing). The plaster composition applied in between the rules is pulled out from the bottom up, and the template is supported by the rules that are fastened to the trunk.

In the same way, the other edge is completed, and then the template is redone for plastering the remaining two edges. Two layer thicknesses are added to the spacing between the rules when they are installed on the plastered edges. As a result, the template is expanded by adding extra bars to the runners on both sides.

The rules are installed at the same distance from the marked line as the edge of the tapering trunk, which has been marked and hung. For columns that narrow, the flutes are removed using a rocking template. The profile board for it is made with a length equal to the edge’s maximum width plus protrusions for the runners. The runners can rotate in relation to the board by at least thirty degrees because of the way they are mounted.

One runner is pushed forward during the pulling of the mortar as the space between the rules gets closer. After turning gradually, the profile board forms an angle with respect to the template’s direction of movement. The flutes and belts that are pulled out automatically narrow uniformly.

Make sure that each time you use a swinging template, only one side advances.

On polyhedral columns

The process of extracting the flutes is done using a template, just like when making grooves on rectangular columns. The template is designed for half of the cross-section in the case of straight columns. On the opposing faces are installed guide rails. When the profile needs to be narrowed, guides are installed on the face next to the one for which a swinging template is created.

On round columns

When creating a stencil, it’s crucial to leave a portion of the flutes (less than half, considering the width of the guide) at the ends of the profile boards rather than belts. This is because the groove that remains after the strip is removed has an easier design. The template is designed to cover 1/3 or ¼ of the section in straight columns. The flutes’ centers are fitted with guide strips. Therefore, it stands to reason that marking and hanging round fluted columns are particularly crucial.

In the event that the flute is twisted, a rope narrowed for entasis is wound onto the trunk to serve as a guide. A swinging template is used to pull out tapering trunks.

The guides are taken out once the flutes are extracted. Using a beveled template, the grooves are sealed with mortar, and the surface is shaped.

It’s critical to modify the plastering technique for different shaped columns, whether they are square, circular, or have more complex designs. To achieve a smooth, even finish that highlights the architectural details, it is important to properly prepare the surface and select the appropriate plaster and tools. Through comprehension of the particular specifications for every type of column, you can guarantee an excellent outcome that safeguards and enhances the structure.

Plastering without a template

As we have previously discussed, plastering columns and pilasters can be partially completed without the need for a template. We will discuss finishing round trunks here.

The ring beacons are installed, and then layers of spray are applied between them, followed by primer application (after it dries). Cutting with a rule and leading it along the beacons around the column levels the solution. Applying the rule follows a zigzag pattern that is akin to plastering wall beacons. Throw the broken mortar onto vacant areas.

If cement mortar was used for the plastering of columns, the ring beacons are removed once the soil has solidified and the same mortar used for the main finish is applied in their place. Using the previously plastered areas as a support for a short rule or spatula, the freshly laid mortar is leveled. Using a concave or straight float, grouting is done.

Plastering columns of any shape—round, square, or otherwise—takes patience and skill. Although each shape has its own special difficulties, the results can improve a room’s overall appearance when done with the appropriate methods.

You can achieve a smooth and polished finish by carefully following every step of the process, from surface preparation to applying the final layers of plaster. Pay close attention to details, such as curves and edges, as these areas frequently need extra caution.

Plastering columns can be a rewarding aspect of your interior design if you have the right tools and practice. The end product will give your area more longevity in addition to beauty.

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