Filling small cracks

Re: Filling small cracks

Dick Coers

I mask off the crack with blue tape and fill it with a sawdust and glue mix. The tape is just thick enough to allow a little overfill, and sands off just right.

Re: Filling small cracks

Dave Bair

Used this method for about 20 years. I tried it once with shellac; not recommended. Couldn't get it to the fill site quickly enough before it set.

Good tip

Re: Filling small cracks

Sgian Dubh

Fredric, you're right that using filler prior to finishing can lead to the problems you describe. It's a well known effect in the finishing business. An alternative to your varnish and wood dust paste is as follows.

* Prep the wood surface.

* Do any dying and/or staining.

* Apply a first coat of a film forming polish, e.g., shellac, lacquer, varnish, etc, and let it dry.

* Fill the holes, small cracks, voids, fissures or other blemishes.

* Let dry.

* Lightly sand over filled area ensuring the filler is removed from open coarse grain if working with such material, e.g., ash, oak. It's a bit easier to ensure all the filler is removed if you're working with fine textured woods such as maple, beech, cherry, etc.

* Continue you finishing routine as normal.

This is pretty standard practice in all the furniture workshops and wood finishing areas I've worked in, and even works pretty well with soft non-film forming finishes such as boiled linseed oil. Slainte.

Furniture industry practice

Bill Tindall, E.Tn.

What I illustrated was sticking a crack back together, no filler necessary.

A crack with an end open, like end of a board, expands and contracts over time. Just filling it with filler of any kind will eventually show as the filler separates from the wood when the crack opens.

For filling voids the furniture industry uses "burn in sticks". These are some low melting polymer, tinted in a great variety of colors. A hot knife is used to melt the stick into the void to fill it. The fill is leveled by hot knife and/or a solvent on a ridged pad.

I have a selection of about 50 colors available from Mohawk.

Re: Furniture industry practice

Don Stephan

If I am reading this correctly, filler will pull away from the wood when the board shrinks seasonally and polymer burn-in sticks will stretch but remain attached to the sides of the crack?

Will traditional shellac burn-in sticks pull away from the wood when it shrinks seasonally or stretch and remain attached?

Re: Furniture industry practice

Dick Coers

Traditional shellac sticks are as brittle as glass, just drop one! No it won't move with the wood.

Re: Furniture industry practice

Sgian Dubh

Bill, I'm not sure Fredric was talking about filling end cracks. He might have been, but he didn't say so. And not all cracks in the wood surface are amenable to gluing back together as you described in a different post.

The use of burn-in sticks for filling voids and other holes is not universally practised to the exclusion of all other hole filling techniques in the furniture industry. Some finishers use them a great deal, others don't. I, in common with many wood finishers I know and have worked with use burn-in sticks only very rarely.

Burn-in sticks are just one of a few options available to woodworkers and wood finishers for dealing with voids, dents, scars, fissures. cracks, etc. Slainte.

The case for burn in sticks

Bill Tindall, E.Tn.

While this thread began describing sticking together cracks/splits that ran out to the edge of lumber the discussion turned to filling voids in general. Apparently few use burn in sticks for this task.

I learned to use these sticks from the woman that did furniture repair at Hendredon Furniture Company. Mohawk, a supplier of materials, teaches classes on the topic. An expert can fill a dent, chip, crack in furniture and even from close up the repair is invisible. However, it takes practice to become expert and I don't claim to be.

The sticks come in may colors. Wood comes in an infinite variety of colors. An expert can melt together a selection of what colors they have to get a perfect match. There is no cure time for the filler. When it is cool it is done, an advantage I find most attractive. On raw wood the fill can be scraped or sanded level. On finished wood the fill is leveled with a pad soaked with solvent formulated to not affect the finish.

Re: Furniture industry practice

Don Stephan

After visiting the Mohawk finishing products page and reading about their three burn in stick products, and re-reading the above post about them, I realize now the above post was a change in direction from the original post in the thread, discussing the use of burn in sticks on "voids" on the surface of a board and not on filling end cracks. My mistake.

Re: The case for burn in sticks

Sgian Dubh

Bill, you've lost me rather because you say "While this thread began describing sticking together cracks/splits that ran out to the edge of lumber … ", I can't see anything in Fredric's original post describing that situation. As I understood his post he talks about 'cracks' without specifying where they occur, e.g., at the end or edge of a piece of wood, somewhere in the centre of a face or edge, and so on.

My purpose in my earlier post was to indicate that whatever the specificity of the void, crack, dent, blemish, etc, there is an alternative method to hide them to that described by Fredric which he might consider, given his experience of not properly being able to remove all the filler from the crack's surrounding grain using other methods: as he noted improperly removed filler surrounding the 'crack' when polished later 'grins' like a sore thumb.

I suspect all that's happened is a small misunderstanding has occurred somewhere because you described gluing together end cracks using dental floss ... but wasn't that in a discussion you initiated(?), and if that's the case I don't really see the relevance of that thread to this one. Slainte.