Tips on Preserving Wooden Fences

Wood rot is induced by a plantlike organism similar to the fungus which causes food spoilage and mildew. Like all other plants, this organism can thrive only if moisture is present. That is why it is particularly important that wood which is in contact with the ground, or which is endlessly exposed to dampness, be correctly protected.  For years the lone effective wood preservative available was creosote.

This bears numerous disadvantages. It leaves an objectionable, lingering odor, and it's got a dark, horrible color which is virtually impossible to paint over. Nevertheless, in later years new kinds of wood preservatives have surfaced which do away with most of the disadvantages encountered in creosote.

While these preservatives are sold under different brand names, most comprise of either pentachlorophenol or zinc naphthenate. They're sold as clear solutions and are often mixed with water repellant to give additional protection to the wood. They not just protect against rot and insect attack, they also bring down warping, checking and swelling. Some also serve as a primer for the wood so that they literally improve its ability to hold paint.

Pentachlorophenol (known as "penta" for short) is generally sold in the form of an oil-base solution which can be put on by brush or spray, or by soaking and dipping. Because the preservative need to penetrate to give utmost protection, soaking or dipping is by far the most effective means of application. Where practical, soak the bottom ends of fence posts and similar pieces by letting them stand upright in a can full of the liquid, or try placing long pieces into a shallow trough made of sheet metal or wood lined with plastic sheeting.

If dipping or soaking is impractical, the preservative must be brushed or sprayed directly onto the bare dry wood. Flood the liquid on, making sure to work it into crevices and into exposed end grain. If the piece is tiny, place a large tub or other container under the work to gather excess liquid which drips off. If you are going to spray the liquid, use a coarse, low-pressure spray. Be sure wear a respirator mask, and spray in a well-ventilated area only.

Wood preservatives which contain zinc naphthenate in a colorless solution are employed in the same manner as those which contain penta. Some of these are exceptionally clear and are made to act as a wood sealer too. They can be used under varnish if a clear natural wood finish will be applied.

Besides applying these wood preservatives to new lumber, the homeowner must also apply them to existing wood structures at sensitive places. For instance, preservative should be brushed generously onto the bottom and top edges of garage doors and entrance doors. Apply also in the joints of wooden porches and steps. Wooden gutters, shutters, storm sash, window frames and fence rails.  All these will benefit from having wood preservative brushed onto exposed parts and joints when paint peels or cracks away.

To reach into tiny crevices and tight corners, like under the door sill, an ordinary pump-type garden sprayer or pressure-type oil can does the job. Keep in mind that wherever two pieces overlap or meet, a pocket is created where moisture is probably to collect and remain. These joints are especially susceptible to attack by fungus, so give them an extra dose at periodic intervals.

When applied to wood which has started to rot, the preservative won't restore the wood that is already decayed. Still, it will effectively stop the rot from fanning out if it is correctly applied. For best results, take out the section of decayed wood completely and replace with a new piece which has been exhaustively coated with preservative on all sides.

Apart from its use on the house itself, wood preservative may be used to protect ladders, picnic tables, garden furniture and similar items. Soak the bottom ends of the legs, and try to apply preservative into the joints where cross-members are secured together or where wood crosses wood. In these joints moisture gets trapped so that the wood continues to be damp for long periods, making conditions ideal for rot to develop.  When putting on penta by spray, brush or dipping, homeowners should avoid contact with the skin because the chemicals will irritate most people.

References:

Log Home Living February 1990
Popular Mechanics Magazine

A Basic Guide on the Different Types of Varnishes

Just as important as the methods involved when applying varnish is the handyman’s choice of the correct kind of varnish. Different types of varnishes vary in their purpose for each job. Most well-stocked paint stores have several different variants, each one designed for one or more specific purposes. To guarantee you are getting the right one for the job at hand, always read the label cautiously, or you may simply ask the salesman at the paint store for other details.

Varnishes differ in many respects. A few are much clearer than others — a significant factor to consider when light finishes are called for. Varnishes also differ in their resistance to water and alcohol staining and in the polish of the final finish. A few dry with an extremely high gloss, while others dry to an absolutely flat finish. For most furniture and paneling a semi-gloss or satin-finish, varnish is preferable. This eliminates the need for rubbing down or muting the final coat.

As a universal rule, the high gloss varnishes have a tougher finish than the duller ones. For this reason, professionals choose to use hard-drying, glossy varnishes on counter tops, table tops and other surfaces which get hard wear. They leave the final coat to harden thoroughly, then wipe it down to a smooth, satin finish which, while still glossy, doesn’t have an unpleasant "wet" shine.

For this type of rubbed finish a special varnish is normally used. Known as a cabinet rubbing varnish, it dries in one day to an exceptionally hard finish which takes on rubbing beautifully. The handyman concerned in trying his hand at this type of finishing process would require some powdered pumice stone, powdered rottenstone and crude oil.

Allow the final varnish coat to dry until thoroughly hardened (check the label for this), then create a paste out of the pumice stone and crude oil. Mix the two together right on the surface, then fold up a heavy, lintless cloth into a small pad. Press this pad into the paste and rub across the surface with straight strokes, along to the grain. Use just a moderate amount of pressure and rub till the surface feels smooth and is free of all "pimples" or flaws.

Next, use a clean, dry cloth to rub all pumice off the surface. Use a different cloth dampened with turpentine to clean up the residue, then wipe once again with a clean cloth till the surface is dry. This will leave the surface somewhat cloudy due to fine scratches which are left by the pumice stone.

To bring back the luster, a second rubbing is needed, this time using powdered rottenstone and crude oil. Mix a paste as described earlier, then rub with a pad of clean felt or similar material. Again rub in straight, parallel strokes which play along the grain. When the surface has been polished to the luster wanted, wipe away all the paste with a clean cloth and polish up with a soft dry cloth till the surface is then clean and dry that the polishing cloth makes a squeaking noise under your hand. Any fine quality furniture polish can then be put on after a day or two.

References:
Paint and Varnish Facts and Formulae by John Norwood Hoff
Old House Journal: Restoration Techniques

© 2011 Athena Goodlight

DIY Tips: Preparations For Wood Varnish Finish

Preparation for a varnish finish should be more thorough than that needed for an opaque painted finish since the transparent varnish will show every flaw in the wood. Sand the surface as smooth as you can and take out all stains or blemishes prior to starting. Dust thoroughly. The fine grit left when sanding is a more common cause of rough-looking, "sandy" finishes.

A good quality bristle brush, absolutely clean, is a must for great varnishing. The brush must be soft and pliant with plenty of flagged bristles. Do not dip it into the varnish more than a third of its length, and always flow the varnish on generously with long strokes put on parallel to the grain. Most crucial of all, do not wipe excess varnish off the brush by dragging the bristles across the rim of the can. Rather, tap the tips of the bristles softly against the inside of the container above the surface of the liquid. Wiping across the rim induces tiny bubbles to form in the fluid and these would make it nearly impossible to achieve a smooth finish.

Air bubbles on the surface likewise can be caused by pressing down excessively hard on the brush. Varnish must be brushed on with just light to moderate pressure. After covering the panel in one direction, make a cross-stroke right away by brushing across the grain in right angles to the original strokes. Finish up by lightly stroking a 3rd time with the grain, using an virtually dry brush and touching the surface with the tips only. This crisscrossing method will almost eliminate all brush strokes so that a uniform application is assured.

Varnishing must never be done in a dusty location, or in garages or basements which are moist or cold. If possible, lay pieces horizontally and always take out all hardware and knobs prior to starting. Chests or cabinets that bear drawers are best done with the drawers taken out so that each one can be placed upright with its front in a horizontal position.


If more than one coat of varnish should be applied, the first coat must be thinned with about ten per cent turpentine. Consecutive coats may then be applied as they come from the can. For a super-smooth finish, sand gently between coats. Use #2/0 very fine sandpaper and rub along the grain. Remember to dust thoroughly prior to applying the next coat. The best way to grab up the dust is to use a tack rag, an especially treated sticky cloth which is available at several paint and hardware stores.


References:
Paint and Varnish Facts and Formulae by John Norwood Hoff
Old House Journal: Restoration Techniques

Copyright © 2011 Athena Goodlight

How To Avoid Paint Peeling and Blistering Problems on Home Exteriors

When you notice paint peeling around the outside of his house, your first impulse is to blame the paint itself. In most cases this is really not so. Nine times out of ten the trouble is caused either by a structural defect which allows moisture to seep in underneath the paint film or by unsuitable preparation of the surface.

While all outside wall paints are made to repel water, they would not stick for very long to a surface which is endlessly wet underneath. If faulty caulking, open seams, leaky gutters or corroded flashing allows moisture to seep into the wall and drench the wood or masonry behind the paint, blistering and peeling is virtually certain to occur. The moisture in the wall is evaporated by the heat of the sun and pulled outward, pushing the paint off with it. This sort of defect is most easily distinguished by the fact that the paint usually peels right down to the bare wood, rather than just flaking off on top.

To fix this kind of dilemma, then you should first fill out or repair all gaping seams and other similar defects. You should then allow for the wall to dry thoroughly prior to repainting. Thorough scraping and sanding is also needed to get rid of the old, defective paint before the new material is applied. Painting immediately over the peeling paint (even when partly removed) will only cause the new coat of paint to peel once more in the near future.

On exterior walls of wood, peeling can often be caused by moisture vapor which gets through the walls from inside the house during times when interior humidity is very high. This often occurs during the winter months when clothes dryers, shower baths and other water-using appliances give off large amounts of water vapor which is cornered indoors by windows and doors that are tightly closed. When this moisture vapor gets to the hollow space behind the siding, it condenses on the cold surfaces and drenches into the wood that leads to peeling later on.

To keep this from happening, you must make every effort to get rid of all possible sources of extra humidity on the interior of the house. Use ventilating fans in bathrooms, laundry areas, and kitchens. If weather permits, open windows at least once or twice a day on each floor.

Since even these measures won’t always prove enough, a lot of experts recommend the use of small ventilating louvers or miniature vents installed in the outer walls. Less than 1 inch in diameter, these vents are set up by merely drilling a hole in the siding, then pushing the vent into place in the opening. One vent is required in every closed-off area between studs to allow vapor to escape freely to the outside without doing any damage.

If only the top layer of paint peels off, leaving the paint underneath still intact, the trouble is most probably due to the paint having been applied when the surface was damp or coated with dust and dirt. This happens oftentimes on the undersides of overhanging eaves, in sheltered parts under roof overhangs, and in other locations which are covered from the weather.

Dirt which gathers on these surfaces is not washed away by wind or rain as quickly as it is on the exposed vertical walls of the house. Due to this, these surfaces must be wiped clean before paint is put on. If these areas are not wiped down with solvent or scoured with detergent solution, the fresh paint will cling to the dirt, instead of on the old paint. As a result, adhesion is really poor, causing paint to peel in less than a year in most cases.

© 2011 Athena Goodlight