How to fix furniture or doors if bleached by disinfectants

We are often told these days that we need to disinfect the surfaces we come into contact with as often as possible. The recommended substances are those based on alcohol or chlorine derivatives, especially sodium hypochlorite (laundry bleach). I received messages asking what to do if, after disinfecting, some pieces of furniture or doors have turned white. I even saw this question on a profile group. So it is a topic of interest and that is why I think the below may be of help.

Why surfaces whiten

Furniture and doors whiten if they are cleaned with spirits. This applies to lacquered objects. Spirits are a solution of ethyl alcohol, which is part of the paint thinner. When you wipe the surfaces, the varnish softens and allows air and water (from the disinfectant mixture) to get inside the film. Hence the white colour. Rapid evaporation of the alcohol causes the varnish to harden again and the air and small water particles remain trapped inside.

The attack of alcohol on surfaces can be different, depending on the concentration and time spent on the surface. If the solution is very dilute (1:3 medicinal spirit in water) or the spirit has had a short contact with the surface, the surface will be very little affected, but disinfection is not effective. Bleaching furniture is only superficial and the traces look like white clouds in the film or white shadows on the surface. Over time the marks fade and if they are only slight white shadows, they will even disappear.

When the disinfectant is concentrated (I've seen the recommendation to use 60-65° alcohol) and the alcohol sits on the surface for a while, the results are very noticeable. The marks are deep white and crumbly. In this case the varnish was dissolved and because the drying was fast, the appearance is similar to gassed film (when dried drops of varnish fall on the still wet film). The film does not recover over time and the surface needs to be repaired.

Repair of very lightly damaged areas

To remove light white marks without depth, we need to remove the remaining water in the film or superficially patch the film. To remove the water, simply heat the film. This can be done with a hair dryer or an iron. We use the hair dryer by directing the air jet directly at the stain and ironing is done by passing the heated iron 3-4 times, without insisting, over a blanket placed on the surface of the furniture. After these passes the blanket is immediately removed to allow the steam to escape. I repeat, to use these methods the appearance of the film must be only slightly whitened and must not have a wrinkled appearance. The white spot looks like a shadow in the film.

The defect can also be remedied locally by sanding the area very gently with a fine abrasive sponge, steel wool or 400-600 grit abrasive paper. After sanding, apply a thin coat of varnish to the affected area only. If the surface is shiny you can also use nail varnish. As an alternative to varnish you can apply a very thin coat of colourless furniture wax which, after drying (2-3 hours), is polished with a soft cotton cloth (an old T-shirt). In order not to have differences in gloss, it is recommended to wax the whole surface after it has been wiped with a mop with water and detergent to remove impurities and shaken.

Remediation of badly damaged surfaces

If the white spot is intense and shaggy to the touch, the lake has been damaged in depth. And if there is a change in colour, the alcohol has dissolved the varnish down to the wood, affecting the berry with which the wood was stained. In this case the only solution is to remove the varnish completely from the entire surface and refinish.

Varnish removal is done by sanding or pickling. Although he has caused the damage, don't try to use alcohol to remove the start of the varnish because it takes a long time and the result will not be as expected. There are commercially available paint strippers that are applied with a brush, left for a while, then the soft film is removed with a squeegee or scraper. The surface is then wiped with a thinner cloth and sanded with a medium abrasive sponge or 180-220 grit abrasive paper. Only after the surface has been completely cleaned can it be refinished.

If the alcohol has not reached the wood and although the appearance is scratchy, no noticeable hole has formed in the film, there is no need to remove the entire coat of varnish. A sanding of the entire surface is sufficient to remove the affected varnish and straighten the surface, after which a coat of varnish is applied with a brush. Sanding is done with a fine abrasive sponge or 280-320 grit paper. If the varnish layer was thick enough and you feel a smooth and continuous surface after sanding, you can apply a layer of furniture wax instead of varnish and polish it after drying.

Recommended products for surface disinfection

There are also varnished surfaces that are not affected by alcohol-based disinfectant. It depends on the resistance of the lake used and its nature. And melamine chipboard is durable. But waxed or oiled surfaces may be affected. Even though alcohol is not a specific solvent for these materials, it can attack them to some extent, soften them and stains can appear on surfaces. Alcohol has but the ability to dehydrate and sometimes stains are the result of wood dehydration. Such stains disappear over time.

For disinfecting varnished surfaces it is best to use cleaning products containing biocides or chlorine-based products. Hypochlorite is one such product that is also good against mould and fungi. It is not used as such but diluted. Hydrogen peroxide (perhydrol) can also be used, and is a disinfectant used for wounds. These products are water-based and do not contain solvents that could attack the lake.

However, the beneficial effects of hot water combined with soap or detergent should not be ignored. The mixture is effective against COVID-19, as we hear every day in the media. This is because the virus is coated with a fatty (lipid) layer which, like any fat, succumbs to water and detergent. But, like grease on dishes, it is not enough to wipe the grease off with a detergent cloth, it must be insisted on. You can also do this with varnished furniture. But you must not let the water stand still because there is a risk that the furniture will stain (turn white). Immediately after washing wipe the surface thoroughly with a dry, clean, soft cloth, preferably cotton (an old T-shirt).

The important thing during this period is to protect ourselves and clean surfaces that could come into contact with the COVID-19 virus. We know little about it (but we are learning new information every day) and until we can fully 'decipher' it the best thing to do is to protect ourselves. Even if we do so at the risk of damaging surfaces that, fortunately, can be restored with effort and losses that are totally insignificant compared to our lives and health.

Take care and stay healthy!