Indy Total Construction

Plaster is an excellent and inexpensive material for giving a smooth, hard surface to an internal wall so that it is ready for painting or wallpapering.

There are many types of plaster, but they can be divided into two basic types: gypsum-based and cement-based. The former are used solely for indoor work, whereas the latter are mainly used outdoors for rendering walls. Cement- based plasters do have a use indoors. however, and that is to finish external walls that might be subject to damp penetration; damp will attack a gypsum plaster and cause it to crumble.

Modern plasters come premixed with lightweight fillers such as perlite or vermiculite, which give a higher degree of thermal insulation and fire resistance and should be mixed with clean water.

Plaster is normally applied to the wall in two layers. The first, called a “floating” coat, is intended to even out the irregularities in the wall surface, so it is kept fairly thick — about 3/sin being usual. The second, finishing coat is spread much thinner Ysin or so — and carefully toweled off to a smooth finish.

Different types of building materials absorb water at different rates and if too much water is absorbed from the fresh plaster, it will dry too quickly and crack.

For example, bricks and lightweight building blocks absorb water quickly and are termed high suction surfaces. On the other hand, materials such as concrete and gypsum board do not absorb water that quickly and are termed low suction. You must choose a plaster to match the surface; but if in doubt, the best thing to do is coat the entire wall with a bonding agent which will make a low suction surface.

Browning plaster should be used for the floating coat on high suction surfaces and Bonding plaster on low suction surfaces. Finish plaster can be used for the finishing coat in both cases.

Only buy plaster as you need it since it has a limited shelf life. A 22lb bag of Browning or Bonding plaster should cover an area of about 1.8yd2 at a depth of 3/sin. The same quantity of Finish plaster, spread thinly, should cover an area about 6yd2.

In addition to a couple of clean buckets and a long level, you will need some special plastering tools: a spot board about 3ft square and supported on trestles or an old table to hold the mixed plaster while you work; a hawk for carrying small quantities of plaster to the wall; a rectangular metal plasterer’s trowel: a wooden float for producing flat surfaces (with a few nails knocked into the end it can double as a “scratcher” for scoring the floating coat before applying the finishing coat): and a 5ft length of 1 x 3in planed wood for leveling the plaster surface.

Cleanliness is essential when mixing plaster. since any dirt present in the mix will affect the drying time. Always use clean tap water for mixing and have a separate bucket of water for cleaning the tools as you work.

Mix the plaster and water in equal volumes in a clean bucket, adding the plaster to the water by sprinkling it on top and breaking up any lumps between your fingers. When the water has soaked into all the plaster, use a thick piece of wood to stir the plaster into a smooth consistency, (Finish plaster should resemble runny ice-cream). and make sure there are no lumps.

Wet the spot board and turn out the plaster on to it, kneading it with the trowel. If the mix appears too wet, sprinkle on a little more plaster and mix in with the trowel.

When working with glass, pay attention to what you are doing and be careful. Wear safety glasses when breaking scored glass. Clean up all debris, broken glass, and glass splinters immediately.

Cutting and fitting glass is called glazing Glazing is actually done in three steps:

• Measuring the frame

• Cutting the glass

• Installing the glass

Begin by removing the old glass. Wear heavy work gloves. Spread some newspaper on the floor to catch small pieces of broken glass. Remove all old glass, putty, glazier’s points, and old paint from the frame. Sand the frame if it is wood or paint it if it is metal.

Measuring is the most important step in replacing a pane of glass. If the piece is cut too small, the glass will fall out of the frame. You cannot trim less than 3/16 inch from a piece of glass that is just a little too big. Measure twice, cut once is a good rule.

Start by measuring exactly the inside of the frame into which the glass will fit. Then subtract 1/8 inch from each measurement (length and width). This allows for irregularities in the frame or glass. Lightly mark the edge of the glass with a three-corner file.

Place the glass on a flat table or special cutting board. Use a T-square or straightedge to make the cut. Allow for the distance from the edge of the cutter to the center of the cutting wheel. Kerosene along the cut line will prevent the glass from splintering.

When replacing a piece of glass, cut the glass 1 /8 inch shorter and 1 /8 inch narrower than the frame.

Use a three-cornered file to mark the dimensions on the glass.

Spread putty over the frame and press the glass into place. Then insert glazier’s points and cover with putty.

Press down hard enough for the cutter to dig into the glass. Once you start moving the cutter, don’t stop until the cut is finished. Use kerosene to lubricate the cutter and prevent the glass from splintering.

Score the glass with the cutter. Then slide the glass over to the edge of the table and tap gently on the bottom side while bending gently. This should be done right after glass is scored! Otherwise the glass should be scored again just before it is finally cut.

Install the cut glass in a wood frame window with glazier’s points and putty. Glazier’s putty or glazing compound dries hard. The putty used on wood frames can be softened with linseed oil. If you’ve used too much oil, remove some by rolling the putty on newspaper.

First spread a thin layer of glazier’s putty inside the frame. Place the glass and press firmly into the putty. Small pieces of wood, called shims, can be. inserted below the glass to center it.

Press glazier’s points into the wood along each edge of the glass. Only a few points are needed because the glass is held in place by the hardened putty, not the glazier’s points. Do not use a hammer to set the points. Press them into place with a chisel or piece of wood. Casement windows use spring clips instead of glazier’s points. Place the clips into the holes provided.

Take more putty and roll it into a rope about 1/4-inch thick. Press it into the joint between the glass and frame. Then finish by smoothing and removing the excess putty with a putty knife.

Glazier’s putty takes a week to harden completely. After that it may be painted. You can scrape off paint smears on the glass with a single-edge razor blade. But it is easy to mask the glass with newspaper and tape before painting.

Glazier’s points are usually set by pressing them into place with a chisel or screwdriver.

Metal frame windows use spring clips in place of glazier’s points. Linseed oil is used to soften putty. Excess oil is rolled out on newspaper. Then the putty is pressed down and the excess removed with a putty knife.