Nicks Painted Furniture: May 2016

THE PROCESS

There are a number of ways to strip the old paint or varnish finish from wood.

· Strip by sanding by hand or a sander

· Strip with a chemical paint stripper

· Strip with a heat gun

Sanding

Sanding to remove old finish or to prepare the wood for painting is an important step in the refinishing process. It is important to use the correct sand paper. A wrong choice can damage the wood surface and make it difficult to repair.

Sandpaper comes in different grades. The grade is based on the number of abrasive particles per square inch that make up the sandpaper. The lower the number, the coarser the grit.

· Coarse – 40 to 60 grit

· Medium – 80 to 120 grit

· Fine – 150 to 180 grit

· Very fine – 220 to 240 grit

· Extra fine – 280 to 320 grit

· Super fine – 360 and above

The general approach to sanding is to start with a coarser grit and then move to a finer grit to remove grit marks left by the coarser sandpaper.Sanding can be done mechanically or by hand. Mechanical sanding is sometimes unavoidable. Small area such as arm rests, table legs and edges must be sanded by hand.When sanding flat areas by hand it is always better to use a sanding block - always sand in the direction of the wood grain. Once the old finish has been removed, the wood must be smoothed with finer sand paper. I like to start sanding with a 150 grit, then move to 220 grit to smooth the wood grain.

When buying sand paper, be aware that you can get dry and wet paper. For paint removal the dry paper seems to be more effective. The cabinet paper in orange is mostly used on wood.

Chemical stripper

This is the most efficient way of stripping old paint or varnishes. There are two types available – solvent based and water based. The water based stripper has many advantages over the oil based strippers. Some of these are:

· Does not severely irritate the skin or eyes

· Equipment can be cleaned with water

I prefer to use a water based striper. It is effective and has virtually no odour. It can easily be washed off with water. It has the following features:

A thick gel formulation that clings to vertical surfaces.
Biodegradable.
Water-based.
Non-flammable.
Contains no ethylene chloride.
Safe, effective, and easy to use.

It is obtainable at all major paint dealers. Just follow the instructions on the container and you can’t go wrong. You might have to repeat the process a few times by brushing the liquid on and after 10 – 20 minutes scraping it off. When the process is finished, the stripper must be neutralised by rinsing it down with sugar soap and water. I use a pot scraper to wash down and remove the remaining patches of paint. When the wood is completely dry you can start with the sanding process. You might find that the wood grain has been raised and to rectify this, the wood must first be treated with a sanding sealer and then sanded down to a smooth finish.

Remember that all chemical strippers can be harmful to your health. So it’s best to use gloves, eye protection and a suitable mask.

Stripping of old finish is a most important step in the process of refinishing. If you do not do this properly, the end result will be bad and in most cases this means that you have to start the process all over again. Once the old paint or varnish is removed the next step is to sands it to a smooth finish – as smooth as possible. Therefore, start with 220 grit sanding paper and finish off with 880 or even 1000 grit. Wipe dust completely and inspect for sanding marks or other blemishes that may remain.

There is another option which does not involve stripping the old finish before you start painting. Provided that the existing finish is still in good shape and does not crack, peel or make bubbles, take the following steps:

· Clean the wood by washing with sugar soap to remove dirt and grease. Wash down with clean water and let it dry.

· Sand lightly with 220 grit sandpaper

· Seal the wood with a clear water based sealer

· When dry, paint with water based paint.

This process is especially successful where the old finish is oil based paint or any lacquer or varnish finish. When you do not seal it first, the water based paint over the oil based paint will result in yellow stains that may appear. This is due to the oil seeping through and staining the paint. To resolve this problem, you can seal the paint and then repaint in the surface again. This should remove the stains.

Using Heat Guns

Basically there are two tools available for stripping paint with heat – heat gun and blow torch. The main difference is that the blow torch has an open flame whereas the heat gun heats air that is blown over the wood.Blow torches are much more aggressive and must be used with care to avoid scourging or burning the wood.

When using either tool ensure that it is held a constant distance from the surface, roughly 6 to 8 inches from the surface. Move the gun backwards and forwards in a sweeping motion. Do not keep the gun stationery on one spot to avoid overheating and scourging the wood. When the paint starts to wrinkle and lift from the surface, it must be removed with a paint scraper. Keep an old container such as an empty tin handy to discard the melted paint.

Repeat the process until all the paint is removed. Use a 220 grit sand paper to remove remaining paint residue and make sure that the surface is clean and smooth before painting.

Remember that the heat can be dangerous when it comes in contact with flammable substances such as thinners. Oil based paints may also give off harmful gases and it is preferable to use a mask, gloves and eye protection.

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