Cyclopedia of Painting/Exterior Painting—Old Work

From Wikisource
Jump to navigation Jump to search

EXTERIOR PAINTING.

Old Work. In repainting an old surface, it is especially important that the contractor consult a practical painter. Carefully examine the surface to be painted before commencing the work and determine whether there is any loose paint or whether the undercoat is in condition to break loose as soon as an elastic coat is applied over it. If the building has previously been primed with ochre, watch out for spots that have received a heavy coat and are ready to break loose. Examine the surface for dampness from basements, drain pipes, down spouts and wet soil. Before starting to paint, see that dampness has not undermined the paint and that the boards do not contain enough moisture to cause the paint to break loose as soon as other coats are applied over them. Look out for loose scales, fine or powdered. They do not appear to be dangerous, nevertheless, they will keep the paint from adhering solidly to the surface and make it soon break away. Be careful about mildew, as this condition is always a sure sign of dampness, and paint applied over mildew will soon spot or peel. Examine the surface to see whether the paint of previous coatings has shriveled. Paint applied over a shriveled undercoating will soon break loose. Prepare the paint according to the surface over which it is to be applied.

Repainting. When the surface to be repainted is in good condition and not cracked or peeled, thoroughly clean the building free from dust, dirt or soot. Wash mildewed spots with turpentine. It is seldom that one mix of paint will answer for all parts of the building. Portions of the house that are the most exposed and weather-beaten should receive the most elastic coat of paint. Portions that are protected, like under porches and verandas, and portions shielded by trees and other buildings, which would render them in about the same condition as under verandas, should receive a coat of paint mixed so as to penetrate the old surface and dry hard and firm without high gloss. If one mix of paint, which will satisfy the exposed portion of the building, is applied over the entire surface and to the protected or hard parts of the building, this oily or elastic coat of paint will dry with a full or heavy gloss, retarding the drying of the second or finishing coat, also causing blistering, checking, cracking and flatting in a short time.

First Coat. For an exposed or weather-beaten surface, the paint should be mixed with 2-3 oil and 1-3 turpentine to assist in penetrating the old surface, as well as parts on which some paint still remains. It should be applied with a full brush to fully satisfy the surface and be well and evenly brushed out so as not to have an excess of paint on the surface where the old paint remains.

The cornices and protected portions should receive paint that is mixed half flat or with enough turpentine to force penetration through the old paint, thus firmly binding this coat to the surface and preventing the second or finishing coat from crawling. The paint should be applied smoothly and evenly and be well brushed in. Do not flow the paint on and expect a uniform coat.

Second Coat. When the surface is thoroughly hard, putty all cracks, seams and nail holes, knifing the putty well in. One mix of paint for finishing coat can be applied over the entire surface. This will dry uniformly. The paint should be mixed to medium heavy and elastic consistency and be well and evenly brushed out.

Cracked and Peeled Paint. Owing to the many kinds of cracked and peeled surfaces, as well as the innumerable causes from which they come, it is impossible to give definite directions for repainting under all of the varied conditions. Judgment must be exercised in studying the surface and treating the same according to its needs.

The following suggestions as to repainting a cracked or peeled surface will meet the most common of both found in the general run of painting.

The preparation of a surface before painting is one of the most important matters to be considered. Properly preparing the surface will often go a great way in assisting to make a successful job of painting over a very badly cracked or peeled surface.

To properly clean a surface, it should be scraped and carefully gone over with a wire brush. The kit should consist of a good scraper and two wire brushes, one stiff and coarse, the other fine and soft. On a surface where the cracks are small and fine, a soft brush will assist in cleaning the dirt from the cracks and leaving the surface in better condition than will a coarse brush. On a surface with large cracks or a peeled surface, a coarse, stiff brush will assist in forcing off the scales, also breaking the peeled edges that have begun to turn out and are sometimes very hard to break loose.

The amount of turpentine recommended in the following reductions is based upon a gallon of hand mixed or prepared paint of a full linseed oil reduction.

Cracked Surfaces. When the paint is cracked in small hair lines, it is usually called crazing of the paint. Generally these hair lines run crosswise of the grain the entire width of the boards to which the paint is applied. The paint is invariably very hard and this crazing is often attributed to an excess of zinc. It is usually caused from an improper reduction or combination of pigments which do not dry uniformly, one being more easily affected by heat and cold than the others, thereby leaving a paint surface which is not uniform as to contraction and expansion. This trouble is especially noticeable on parts of work that have to withstand a great deal of vibration. If the paint has not been applied too heavy and upon examination is found to be perfectly bound to the wood, it can be successfully repainted in the following manner:

A great deal of care should be taken in the preparation of the first coat, as the surface is usually hard and brittle. If the paint is mixed half flat it will have sufficient turpentine to penetrate well into the undercoats, and if well brushed will thoroughly bind to them.

The finishing coat should be of good consistency and well brushed. It should contain from 1-32 to 1-16 gallon of turpentine to a gallon of paint, as the paint should nut be too elastic, otherwise it is liable to blister on this hard surface if exposed to heat when fresh.

Paint found to be cracked only through the top coat, the checks not running through to the work, makes a very treacherous surface to repaint, as the first coat applied is liable to penetrate only through the hard glaze which has already commenced to crack and possibly breaking loose from the undercoats, and when a second and more elastic coat has been applied this glaze will break loose and cause the last coats to peel. The first coat should be mixed with 14 gallon of turpentine to the gallon of paint, so as to penetrate, if possible, the glazy surface to the undercoats which are more firm, thereby binding itself as well as the finishing coat to the surface. The finishing coat should not be applied too elastic. This is to avoid having an excess of oil on the surface.

Large and deep cracks, running to the primer or undercoats, are usually caused by coats being applied too rapidly, not allowing sufficient time for proper hardening, or undercoats being mixed heavy with boiled or rosin oil or an excess of japan which did not allow the paint to properly harden and left the under-surface soft and spongy. Such paint is usually tough and elastic and the undercoats are found to be spongy and easily affected by hot or humid weather. This paint usually shows no signs of peeling, as it is very tough and seems to be firmly adhering to the wood, but to repaint the surface requires a great deal of care in keeping the new paint from following the first coats and cracking in like manner. Be careful not to have an excess of paint on the surface, as such will blister and peel.

Thoroughly clean the surface with a wire brush. Mix the first coat of paint fairly elastic or with 1 pint to 1+12 pints of turpentine to a gallon of paint. This will not dry too hard and will be sufficiently elastic to withstand contraction and expansion over this treacherous surface, also penetrate to a good depth. Brush out well and do not attempt to fill the cracks with this coat. The finishing coat should be mixed to a good consistency with 1-32 to 1-16 gallon of turpentine to the gallon of paint and be well brushed over the surface. If, however, all of the old paint is solid and dried through, a half-elastic coat, 14 gallon of turpentine to a gallon of paint, can be applied and should be well brushed into the cracks. This will dry firm and hard and a second coat of elastic paint can be applied over it. This, well brushed into the cracks, will to a certain extent fill them and make a very passable job without danger of blistering, which would be the result if a first coat of very elastic paint had been applied.

Alligatored Paint. Where the paint is cracked in every direction, forming blocks, triangles, and in fact, every conceivable shape, it is called alligatoring. This comes from a number of causes, but can usually be traced to non-drying undercoats and heavy coats of different mixtures. Ochre or similar slow-drying pigments mixed with boiled oil will very often be found at the bottom of this trouble. Fatty paint or the use of adulterated oil also causes paint to alligator. Such paint is usually tough and hard except where it is well protected and there the undercoats will be found to be tacky and spongy. The only successful way to repaint this surface is to burn off the paint. This is a very difficult job, as the heat softens up the excess of oil and a gummy, sticky mass of paint is the result. This soon gums the knife, also forms a cement over the wood, which is very hard to remove. This is especially true where excessive painting has been done, the paint having been mixed with boiled oil or an excess of japan added, or where the paint has cracked when first applied and paint heavily applied over it in an attempt to fill the cracks, leaving the surface with an excess of oil paint spread over it.

If it is not possible to burn the paint off, it can be painted with fairly good results if first cleaned with a wire brush, breaking the edges of the paint that may have commenced to show signs of peeling and turning out, also removing all the dirt from the cracks, then applying a coat of paint mixed with from a pint to a quart of turpentine to the gallon of paint, according to the elasticity of the surface. Do not apply a heavier coat than is absolutely necessary. Be particular to brush the paint well. Do not have the paint too flat on the protected or more elastic portions of the building, as these parts are very easily affected by hot or humid weather. Do not attempt to rush the work. Allow ample time for the paint to harden, then apply a finishing coat of paint mixed to a good consistency reduced with 1-32 to 1-16 gallon turpentine to a gallon of paint. Brush out well. This will not blister nor pull the undercoats and will make a fairly satisfactory job.

Peeled Paint. In preparing the surface for the repainting of peeled work, the same care should be exercised as with cracked paint. Where the paint has commenced to peel in small chips and upon examination it is found that the trouble is with the last or finishing coat, such is called chipping or fluffing. The trouble can usually be traced to the improper application of the paint or its having been applied over dampness caused by dews or frosts, also the paint becoming chilled or applied in freezing weather, not allowing sufficient penetration, which caused it to soon chip or fluff off. This trouble can very easily be overcome by scraping or going over the building with a wire brush and coarse sandpaper, removing all the loose paint and then applying one coat of paint of good consistency mixed elastic with 18 gallon turpentine to the gallon of paint. This mixture will thoroughly penetrate and bind to the undercoats, generally making very satisfactory work.

If the paint is peeling in small thin scales and the trouble only goes as far as the priming, it usually will be found upon examination that this coat was of material like yellow ochre which has been applied heavy and dried with a gloss, the second coat not reduced with a sufficient amount of turpentine to penetrate the hard surface. To repaint this surface, the scales and loose paint should be scraped and brushed off and a coat of paint, mixed with sufficient turpentine to penetrate the priming coat, applied over the spots where the paint has peeled, then apply a well brushed finishing coat over the entire building. This should not be too oily or elastic, otherwise it will break loose from the undercoats, but it should carry from 1-32 to 1-16 gallon turpentine to assist in brushing and penetrating the old surface.

Where the paint is peeling in patches, exposing the bare wood, and it is found upon examination that the backs of the scales have a heavy coat of ochre or some other dry pigment which is absorbing the oil from the wood, and the paint has not been applied uniformly and is breaking away in spots, these places can be scraped and thoroughly brushed, then a coat of paint mixed with a percentage of turpentine to assist in penetration applied over these spots. One coat of paint can then be applied over the entire building, if the surface is in fair condition, and the undercoats have not been applied too heavily. However, if the building has been standing and one coat is not sufficient, the first coat should be mixed half flat so as not to leave an excess of oily paint on the surface. This will even up the work and an elastic finishing coat can then be applied over the entire building.

When a building has been painted a number of times and the surface is peeling to the bare wood, the only satisfactory way to repaint this is to burn the surface to the wood, following special instructions given for burned surface.

Where the paint has peeled in spots from dampness, caused either by wet basements or plaster, the surface can be successfully repainted after the house has been allowed to dry out, by cleaning it and touching up the spots where the paint has peeled, then covering with one coat of paint. This will even up the surface and avoid repainting the entire building if only part of the house is peeling.

Repainting a Surface on Which the Paint Has Been Burned. Where paint is peeling or cracking badly, the only satisfactory way is to burn the paint to the bare wood. This leaves all of the surface practically new, and if the character of the work is understood good results can be accomplished, but it must be borne in mind that all paints when burned do not leave surfaces in the same condition and the resulting character of each must be understood before mixing the priming coat. Where an excess of boiled oil has been used in successive repainting and the work has commenced to crack or alligator, it will be found very hard to get the work in good condition, as the oil will set on the surface and form a glaze which is very hard to penetrate; likewise where fatty oil or paint with a percentage of gloss or rosin oil has been used. While the heat of the burning lamp softens the oil and paint, it is very hard to remove all of it from the surface.

To repaint this surface, care should be exercised in thoroughly sandpapering and scraping or breaking this glaze where it is possible and a liberal amount of turpentine should be mixed with the first coat to force penetration through this hard surface. Where dry ochre or similar primer has been used, causing the paint to peel from its not having penetrated the surface, only a small proportion of oil having gone into the wood, it is very easy to remove with a burning lamp, leaving a surface which is practically new, as most of the oil will have been drawn from the wood during the process of burning. This surface can then be treated the same as any new wood, with possibly the exception of some protected parts where the oil has penetrated to a greater depth and the paint is in better condition than on exposed parts. The cause of blistered and peeled work can often be traced to too elastic a coating of paint having been applied over a burned surface. This is especially true where boiled or heavy oil has been used in the primer of the paint which was burned. Boiled oil should never be used in a paint applied over a burned surface, it will not penetrate but will lay on the surface and will soon crack, blister and peel. These troubles are often laid to dampness or the paint used, or some defect in the building which supposedly did not allow the paint to properly harden, while the true cause is from the paint not having been properly reduced or applied over the surface.

Blistering. When paint blisters, the cause is usually attributed to dampness, and it is perhaps true that more trouble of this character on new buildings can be traced to wet or unseasoned lumber or fresh plastering, than to any other cause, and on old buildings to bad roofs, leaky gutters, broken down spouts and wet basements. There are so many chances for dampness to get under the paint of either new or old buildings that it naturally follows there would be more blisters from this cause than from all others.

As to buildings being in the foregoing condition, the weather before and during the time the paint is applied has much to do with it.

Dampness causing blistering of paint is more easily detected than any other condition. This is especially true where the dampness comes from wet plastering, as the blisters will be full of discolored water which stains the paint when they break, and upon removing the paint over the blisters it will be found that there is very little, if any, paint or oil left in the grain of the wood. When examining surfaces where the water or dampness is not perceptible at the time of the examination, it is safe to assume, without fear of an error in judgment, that dampness has been the cause of the trouble, but there are also many other causes for paint blistering which are often laid to the foregoing.

Where linseed oil has been used from the bottom of a tank and the settlings or foots are mixed with the paint, it will cause blistering. This has the appearance of dampness, there being spots where the paint has not penetrated and the surface is almost bare. This paint will sometimes pull away in large blisters, the underneath of which show that the paint has adhered to the surface but contained something which would not allow of solid drying. This trouble can be attributed to non-drying mucilaginous matter which separated from the linseed oil and did not allow of uniform penetration, binding or drying. Such blisters are invariably oblong and follow the grain of the wood.

New linseed oil will often cause the paint to blubber in very warm weather, these blubbers causing small blisters, that is attributed to the moisture in the oil which the heat draws out in the shape of different sized blubbers, breaking and forming small blisters when the paint is dry.

Paint mixed with rosin oil will blister under extreme heat. Paint applied over old work blisters more often from the application of excessive oil coats than from any other cause outside of dampness. As stated before, dampness is easily traced in either old or new work. Numerous coats of oil paint will often blister very soon after the paint has been applied. The back of these blisters will show that the paint has at one time been dry and was hard enough to hold to the surface, but when paint was applied over it, it could not stand the tension or pull of the other coats. This is caused by numerous coats of oil paint which do not thoroughly cement together and form a solid foundation. This can be proven by the backs of the blisters which often have glossy spots that would not show had the coats of paint thoroughly cemented or adhered. Other parts of the blisters show gummy points, proving the paint had once been cemented together in spots. This also shows that the paint was over-elastic and had pulled away from the surface by the heat which broke the coats apart. This latter trouble is sometimes called a splitting of the paint. An excess of oil on a hard surface like ochre priming, where there has not been sufficient penetration, will cause the paint to blister on protected parts of the building, such as underneath porches, etc. This trouble is very hard to understand, but the true cause is excessive heat on a porch or veranda floor, reflecting on the sides of the building, causing blistering or the raising up and breaking loose of the paint from the under-surface, this is especially true where the sun reaches porches and verandas which have an enclosed end, preventing free circulation of air and causing intense heat.

Blistering sometimes takes place from excessive painting on the sides of buildings where the sun does not reach. This is caused by radiation of the heat, which is very intense at certain times of the day, and no free circulation of air, also from stone or cement walks which become very hot from the rays of the sun, radiating this heat and blistering the paint for some distance above these walks. Freshly painted veranda floors will reflect enough heat on the side of a building to cause the paint to blister and break away. Veranda ceilings will sometimes blister. The cause can be traced to water which has been thrown on the floor or to pools of rainwater which reflect the heat of the sun on the ceiling, forming a lens the same as would a convex glass if laid in the same position. This reflection will cause the paint to blister on ceilings and the trouble is often misattributed to leaky roofs, gutters or like causes.

Blistering Over Ochre. If a coat of oil paint is applied over a heavy coat of ochre priming which has dried hard and flinty, it will often cause it to blister badly when exposed to the heat of the sun. This result is due to the paint not penetrating into the hard surface, thus leaving an excess of oil on the ochre coat. Where ochre is mixed dry with oil, it is impossible to thoroughly incorporate the two and when applied will sometimes raise up in small blisters: the under part will be found dry and the paint can be powdered. This is caused by the dry ochre lying on the surface, absorbing all of the oil and leaving nothing to satisfy the wood, consequently, the heat of the sun will soon pull it away. This is more noticeable after another coat of paint has been applied over the priming.

To successfully repaint blistered work, the character of each kind of blister must be understood; study the cause of the trouble and repaint the surface accordingly. If water or dampness is the cause, the paint for retouching should be mixed with a full oil reduction to satisfy the bare wood; if from fat oil, it must be mixed with sufficient turpentine to penetrate the surface which this oil leaves; if from fatty or non-drying oil, the surface must be first washed with turpentine to remove the grease, then touched up with paint mixed with part turpentine to assist in penetrating to a good depth.

For ochres and like surfaces, the same directions apply for touching up as for a peeled surface. On old work where the paint has blistered from an excess of oil, retouch with paint mixed half flat. This will penetrate through the old paint and give a good foundation. After the work on the foregoing has been touched up, the entire building can be given a coat of paint: this will even up fairly well, but the spots caused by the blisters will show to a certain extent.

Roof. Do not paint damp shingles. Allow time for rain, dew or frost to dry off and the roof to become thoroughly dry. Sweep the roof with a good broom and remove all dirt, lint, cinders and soot.

The mix of paint depends upon the condition of the roof. Use good material reduced with raw linseed oil in painted shingled roofs.

On old shingles apply a uniform coat of paint mixed to the consistency of satin. It is necessary to have the paint of a very thin consistency to fully satisfy the old weather-beaten shingles. When thoroughly dry, apply a finishing coat of heavier consistency, well worked into the cracks.

If the roof has been previously painted or the shingles dipped before laying, and are in a fair condition, the paint can be used of heavier consistency and one coat is usually sufficient to do a satisfactory job on this surface.

It is sometimes claimed that a roof has faded or spotted out in a comparatively short time. This is more often the case where combination pigments which go to make up greens or olives have been used. In the majority of cases such complaints can be traced to the color not fading, but the oil having been absorbed by the shingles, these not having been fully satisfied by the undercoat reductions. A little oil rubbed over the surface will demonstrate that the full color is there but has flatted out through having been robbed of the oil required to bring out the original shade or brilliancy.

Foundation and Flues. Foundations or flues which have been painted should be treated the same as new work. Where foundations or flues have been kept painted, with oil paint, one coat of similar color mixed to a good consistency is usually sufficient. This should be applied after the house has been finished. If previously finished in flat color and is to be painted again in the same manner, one oil paint coat of good consistency and one coat of flat color should be applied.

Window Sash. Break sashes loose so they can be worked without trouble. Scrape off all loose paint and putty, then sandpaper. If the putty is soft or broken away, it is best to remove all and not attempt to patch up broken places. Apply a heavy coat of paint in the groove where the putty has been removed. The same paint used for trimming or body color is often used for this coat, but should usually be of a heavier consistency and requires a different mix, however, where blacks or reds are used, it is a good idea to have a groundwork of dark lead color for black and terra cotta for reds. If the sash is in good condition, not badly weather-beaten, the paint should be mixed half flat and a finishing coat of black or red varnish color applied. Before applying this finishing coat, reputty the sash where necessary. If the putty is to be painted, it is best to reputty some days before tracing, so it will become set.

Outside Blinds. Remove blinds from the building and examine the slats to see whether they will work. If stuck together from previous painting, they are sometimes very difficult to break loose and require a great deal of patience to keep them from breaking. Use a sharp knife and cut in between the slats, also at the ends. Break one slat loose at a time. As soon as broken loose, cut or scrape the old paint from the edges of rails, also ends of slats, and break the paint from around the staples on stick so they will work freely. Sandpaper exposed parts and dust off thoroughly. If the blinds have been closed and the inside is in good condition, they will require only one coat of paint on this part. Exposed and weather-beaten parts should receive the first coat of paint of medium consistency mixed with 2-3 and 1-3 turpentine, well brushed out. The ends of slats and inside of frame work do not need this coat. After the first coat has become hard dry, the blinds should receive a coat of paint all over. The paint should be of good consistency and be well brushed out so as not to have an excess of paint, causing the slats to work hard. Leave the slats open until the paint is dry. If closed, they are very apt to stick.

Veranda Columns and Rails. Be sure that the surface is dry. Scrape and sandpaper loose paint from veranda columns and rails before first coating. Fill the cracks and nail holes with paint. See that there is no mildew on the base, skirting boards or lattice work caused by dampness underneath the porches and verandas. Knife putty into cracks and nail holes before applying finishing coat. Use the same paint as for the building, well brushed out on the round columns and turned work.

Veranda and Porch Floors. Sweep the floor clean, also remove dirt from cracks so that the paint can be brushed into them. Paint applied too heavily on floors will not dry solid and will soon scuff up. Be sure there is no dampness coming from underneath, as such will cause the paint to blister or peel and not allow of proper hardening. It is very hard to avoid blistering in the repainting of floors that have been kept oiled. First wash the floor with turpentine and wipe off dry, then apply a thin coat of paint mixed half flat. Allow ample time for the paint to harden, then apply the finishing coat mixed with 2-3 oil and 1-3 turpentine, well brushed out.

On old floors that have been kept well painted, one coat is often sufficient. Where they are badly weather-beaten they should receive a coat of paint of good consistency mixed with 2-3 oil and 1-3 turpentine. When hard dry, putty the cracks, nail holes and seams, then apply a coat of paint of heavier consistency mixed with the same proportions of oil and turpentine. The floors and steps should not receive the finishing coat until all of the other painting has been completed.

The fence should receive the same care as to preparing the work for painting as the building. Sweep and dust the work thoroughly before painting. The same mixture of paint should be used on the fence as on the house and the fence trimmed with the same color.

Old Work—One Coat. Where the paint has stood for two or three years and one coat is to be given over a shade similar to the one already on the building, the surface should be thoroughly cleaned with a wire brush or broom, then thoroughly dusted. It is sometimes necessary to wash the surface with sponge and water to remove the smoke and dirt, which otherwise will work up through the paint, changing the color and making un-uniform shades. It is almost impossible to brush dirt streaks out and the only way to get the work in condition for painting is to first wash the surface with water. Allow time for the surface to dry, then, if the wear of the paint is found to be uniform, one coat mixed to a good consistency with a full oil reduction and sufficient turpentine to assist the working will make a satisfactory job. If, however, upon examination the paint is found to be weather-beaten or wearing off in spots on the exposed parts, the building will have to be touched up on these exposed portions and a coat of paint applied to the entire surface to even it up; otherwise it will be spotted when the paint has dried out, making an unsatisfactory job.

If the paint has not worn down to the wood and is only worn off to the undercoats which are solid, mix the paint with half turpentine and half oil, go over the exposed portions of the building with a smooth, even coat, and as soon as hard dry give the entire surface a coat of paint mixed to a good heavy consistency, as before directed. The paint should dry out even, thus making satisfactory work.

As all portions of a building do not have uniform exposure, it is very hard to find a surface where one coat will produce satisfactory work over the entire building. On the most severely exposed parts of a building, the paint will naturally show more wear than on the protected parts and these exposed parts will need to be touched up or painted over to even them up with the less exposed portions.