Q. We have a concrete patio at the rear of our house. It had a few cracks, which we patched. The patches are a different color than the concrete so we want to paint the patio. It has a grease stain where a barbecue once set, but we can cover that with a stain-killer primer. Can you give us some tips to get a good paint job?
A. Concrete painting has its own set of techniques, some of which differ considerably from other types of painting. For example, you do not want to put a stain-killer on the grease stain – you should remove the stain with a degreasing cleaner, which you can buy at most home centers or auto-parts stores. Concrete floor paint is designed to withstand adhesion and adhere well to properly prepared surfaces, and usually it does not need a primer.
Several versions of concrete floor paints are available, including highly durable epoxy, but most do-it-yourselfers prefer water-based (latex) paints because they have less odor, are easier to work with, and easier to clean up (with soap and water). Examples of popular Di y patio paints are Behr Porch and Floor Paint and Drylok Concrete Floor Paint (caution: do not confuse this with Drylok Masonry Waterproofer, which is not intended for floors).
The next step is to clean the concrete thoroughly. Again, you can find special cleaners for this, or you can use a heavy-duty household detergent. After cleaning, rinse the concrete and let it dry well.
Before using paint, you should read the directions and cautions on the label. Most concrete paints advise checking the surface for smoothness; rub it lightly with your fingertips to test the texture. If the surface has a slightly rough or gritty texture, something like sandpaper, you are ready to paint. A surface of this type will give paint good adhesion.
If the surface is very smooth, you’ll need to use a chemical etch to get the proper texture. Etching liquids, some of which contain muriatic acid, are sold at most paint stores; follow directions on the container for proper use and observe all cautions.
The final step, when the surface is ready, is to apply the paint. Some manufacturers recommend using a brush, so the paint can be worked into the small pores of the concrete.
The weakest spot in your project might be the patched cracks. Settlement cracks tend to widen in time, and the patches will probably loosen and have to be replaced. Be sure and save some paint for touch-ups.
Q. Can high-performance air filters harm my heating equipment? A guy who cleaned our furnace recently said they can.
A. Most experts agree that air filters made by reputable companies won’t harm heating-cooling equipment as long as they don’t get too dirty. That includes high-performance filters, which are designed to screen out some very tiny allergy-causing particles.
If any filter becomes too dirty, it reduces the air flow to the fan and can boost your heating-cooling costs as well as potentially cause excessive strain on the fan motor and some of the controls.
I have heard of cases where heating plants quit working because of clogged filters. The remedy is to check filters regularly – at least once a month – to see if they have accumulated excessive dirt, and change or clean them when necessary.
It doesn’t pay to rely too much on manufacturer’s claims that a given filter will last for a specific time.
Before installing a new filter, I look for a blank space on the rim and write the installation date on it. I use pleated filters, and while a visual check is the best way to look for dirt, I discard an old filter after a few months even if it doesn’t look too dirty.