How to Repair a Crack in French Polish

So, your French polished tabletop has a nasty crack in it. Obvious answer is to send it out to a professional restorer, but that can be expensive. Why not have a go yourself - what's the worst that could happen!

If the top is sound, then this really is worth trying - if the top flexes at the crack then that should be sorted first.

There's a 60sec video available too

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You'll need:

Cleaning mixture: Four parts white spirit to one part linseed oil (removes dirt and wax, but not finish)

Coarse cloth for cleaning

Wooden tooth picks for cleaning out the crack

Shellac stick of a similar tone to the wood, to fill the crack

Iron (soldering iron or similar)

Masking tape

Sharp chisel and card scraper, or similar, for leveling the filler

Fine abrasive paper, to feather repair area

French polish (ready mixed, or made by dissolving shellac flakes in methylated spirits (25g/100ml))

Rubber (soft cotton pad or cotton wool, wrapped in a lint free cloth), for applying polish

'0000' Steel wool and furniture wax, to match the finish with the rest of the piece

You need to remove all the dirt and wax from the tabletop and crack

Dampen a cloth with a mixture of four parts white spirit to one part linseed oil, and use this to clean the top. As the cloth gets clogged with dirt, keep replacing it. At the same time, use the tooth picks to clean out the crack.

Once the cloths and tooth picks no longer pick up any residue, give the tabletop a final wipe over with a cloth dampened with just white spirit (this will clear up any linseed oil)

This is optional, but I lay down a few coats of polish at this stage. These will provide a little extra protection during the repair

Mask around the crack with some low-tack tape. This gives a reference for chisel in the next step, and prevents excess filler sticking where it's not needed

Now apply the iron to the shellac stick, and dribble the melting filler into the crack, taking care not to get the iron in contact with the polished surface

Don't worry if it isn't an exact match. You can apply tiny dabs of a spirit stain to the filler if you like, and the following coats of polish will help to blend it in

The dried filler will be proud of the tabletop, and will need leveling

Resting the back of a chisel on the masking tape will allow you to safely pare away most of the excess

Remove the tape, and then use a card scraper, or a slightly curved blade, to carefully remove the rest of the excess filler

The top should feel perfectly flat when you're done

Very lightly feather the area of the repair with fine abrasive

Wipe the entire surface clean with a cloth slightly dampened with white spirit

French polish can be bought ready mixed, but watch out for a use by date.

Alternatively, buy shellac flakes and dissolve them overnight in methylated spirits. A ratio of 25g/100ml is about right

The polish is best applied using a 'rubber', which is a pad of lint free cloth around a cotton wool reservoir. The polish is added to the reservoir, bit by bit, and the pad compressed by twisting, until a fine film of polish appears through the tightened cloth

When not in use, store the charged rubber in an airtight glass jar

The polish is applied by sweeping the rubber onto, across, and off from the surface, in slightly overlapping strokes

Several coats, as a minimum, should be applied, allowing ten to twenty minutes drying time in between

A final finish using just a methylated spirits charged rubber can help unify the surface, if it doesn't look too good

Tip: A drop or two of linseed oil on the face of the rubber can help avoid it sticking to the surface during polishing

Complicated, loose, and tight, figure of eight application techniques require some practice, and are best left to the experts (of which I am not one!)

The pristine polished surface you've produced (hopefully) might look out of place against the rest of the piece, which will have aged over time. A light rub with '0000' steel wool and furniture wax should sort this out. Buff off the wax vigorously with a clean cloth

The difference between the before and after pictures here should be pretty clear

Hope you found the Instructable useful. If you did, then please consider voting for it in the 'Before & After' contest

Cheers,

Mitch