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Filling cracks

olaf Vogel

olaf Vogel

Joined
Mar 10, 2015
Messages
347
Likes
150
Location
Aurora, Ont, CA
Website
www.revolvingarts.ca
I'm trying to finish up a piece of heavily spalted maple, the wood is already dry.
The plan is to finish it with shellac.
But it has a few cracks that I would like to fill.

Q1 - Is epoxy the best to use for filling? I have some high strength West Systems left over.
Q2 - To keep the filled spot from spreading and causing staining when I finish, should I apply shellac first, then fill the cracks? or Fill first and finish second?

IMG_1436.JPG IMG_1437.JPG
 
First, given that the wood is dry, it should be fairly stable. In this particular case, the crack follows the growth ring and in my opinion isn't likely to change. A crack that is transverse to the growth rings would be of greater concern than this one. For aesthetic reasons it would be good to fill the defect if you are planning to have a glossy finish. You could use epoxy or CA, but first apply a wash coat of shellac to prevent local staining. I like to use Starbond Brown Medium CA (actually amber) for filling this type of defect because of its resinous appearance.
 
Recently I got out a tool I built that I used a Locktite heavy duty epoxy from the BORG. I built the tool and put it away maybe last winter. When I tried to use it the epoxy was crumbling. Did I have a bad batch, a bad mixing job, bad luck? I don't know. But, that was definitely a bad experience with epoxy.
Just putting it out there.
 
Have you used shellac on this kind of wood before? Just curious because I would just use a flat sheen artist fixatif to maintain that color. I usually use masking tape to tape off a crack like that, and fill with a fine sawdust/Titebond original mix. I mix it pretty dry, as much sawdust as it can hold.
 
Bill Boehme said:
For aesthetic reasons it would be good to fill the defect if you are planning to have a glossy finish. You could use epoxy or CA, but first apply a wash coat of shellac to prevent local staining. I like to use Starbond Brown Medium CA (actually amber) for filling this type of defect because of its resinous appearance.
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Thats exactly what I was looking for. Thanks!
I'll stick with epoxy for now as I've not had great luck with CA for this.
 
You could try and match the color of the wood you are filling with the darker saw dust and wood glue.
Or since you have spalting on the wood piece you could use a black pigment or black saw dust mixed
with wood glue and fill the void and make it look like spalting.
You can also add pigment to epoxy and accomplish the same affect.
The wood glue solution is quick to test, mix up saw dust and wood glue and plug some drilled holes
and let it dry and sand it smooth. This will allow you to figure out ahead of time how much and
how dark of wood dust to add to get the desired affect.
 
Olaf,
Epoxy is the way I’d go and in my experience it doesn’t really soak into the fibers and ruin the finish the way CA does. Soooo, I don’t think any pre-finish before the epoxy is necessary — however, it wouldn’t hurt any if you are wanting to put a barrier coating of shellac as epoxy sticks to just about anything.

Raul,
Crumbling epoxy sounds like mismatched resin and hardener. Poor mixing usually leads to a sticky, non-curing mess.
 
Raul McCai said:
Recently I got out a tool I built that I used a Locktite heavy duty epoxy from the BORG. I built the tool and put it away maybe last winter. When I tried to use it the epoxy was crumbling. Did I have a bad batch, a bad mixing job, bad luck? I don't know. But, that was definitely a bad experience with epoxy.
Just putting it out there.
Click to expand...

Raul, I use the Loctite for lots of things and haven't had any failures to date. Was this a wood to wood bond, wood to metal or something else? I can tell you that sometimes it is finicky if you don't use equal portions so I weigh it with a little portion scale that I used to use in my bakery. Goes down to .1 gram but you can get one even more precise on Amazon for a few bucks.
 
For those using either epoxy, or wood glue mixed with sanding dust.......Do you think it makes any difference to the final appearance, or adherence, how fine the dust is? At what stage of the sanding process, do you collect a specimen for this purpose? I think we can generally accept the premise that sanding dust collected from the bowl that will need a crack filled would be the best bet for ending up with a filled crack that best matches the wood.
 
Whittle some wedges of wood, touch some medium CA cleanly into the gap, then slip the wedge(s) in until it fills. Don't wipe squeeze out, cut it later. If the grain orientation's different where the crack is found, make the wedge accordingly.

My second choice is bark shavings, where bark is present in the piece, followed by crushed bark.

The type of finish can give you the dead fish eye look if you use dust. Too much scatter.
 
Coffee grounds make a nice filler with epoxy or CA.

Ed Brannon taught me this trick.
When Ed Brannon asked to use some coffe grounds I thought he had lost his mind.
The result of coffe grounds is a realistic looking defect in the wood. The texture and color of the grounds looks like a water stained rot spot.

If you have the ability to make a crack disappear go for it. I always seen them.
I gave up on hiding cracks - I now try to make them look like they were always there.
Turn them into a natural looking defect
 
I'm not sure what I'll do with this black and white ebony bowl.....the darn thing cost me $97 after shipping. :(

Mixed the epoxy with sanding dust, and I probably should have used more of the dust than I did. Can't really tell how it'll look until after it's dry and sanded flush......so, you get what you get!

Here's the biggest crack.....it's about 3/32" wide. There were several other small cracks that were also filled.
IMG_2459.JPG
The bowl was finished this morning, except for the foot. This is with danish oil applied, no wax yet. I'm pleased that the crack appears somewhat camouflaged by the wood, but it still looks like a crack.
IMG_2472.JPG
IMG_2471.JPG
Not sure what I'll do with this bowl at this point......... Sure would love to have some of this B&W Ebony that didn't split, but I heard this is a problem for this species. My sources usually only have spindle blocks on rare occasions.....mostly nothing good enough to make a bowl from.
 
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Beautiful bowl. I agree the epoxy should be a little darker but most people won't notice. I have patched some cracks with epoxy, I use Transtint Dye. It just takes a small amount to get a nice black finish. Usually a couple of drops on the end of a toothpick. I use the five minute epoxy and only mix a small amount at a time. I don't think you will have any problem selling the bowl.
 
Odie,

That is a nice looking bowl, if you did not know the crack was there you would need to look
for it to notice it. I have seen some nicely done pieces where they used turquoise, silver, bronze
or copper powder to fill in cracks and voids. With the black variations in the wood grain your
solution looks as good as any other solution available. You could cradle the bowl in a three legged
stand which would cover the crack on the outside of the bowl.
 
Personally I don't like the sawdust crack repair on larger cracks. It looks like you filled it with pressed wood, not a good look. I do however use contrasting sawdust sometimes. I keep several jars with rich color wood sawdust such as ebony or redheart. I will use these. Still I prefer to use either the bark as or coffee grounds as suggested above. To me it makes a more natural look. I do like the look of colored epoxy and use that a lot. A crack running horizontally across the existing grain is impossible to hide so your much better off trying to make a feature out of it. Sometimes that needs using a dremel to reshape the crack so whatever filler you use will be come a highlight.
 
Plus one for ground coffee and epoxy (I use 30-minute and fill proud of the final surface).

Depending on brand and grind, the coffee has light and dark portions; when cut and sanded, it looks like miniature Terrazzo.
 
Joe Greiner said:
Plus one for ground coffee and epoxy (I use 30-minute and fill proud of the final surface).

Depending on brand and grind, the coffee has light and dark portions; when cut and sanded, it looks like miniature Terrazzo.
Click to expand...


Joe, what brand of epoxy do you use?
The HD version I tried is terrible. The West Systems is good but takesovernight to harden.
 
Joe, I use the five minute epoxy for almost everything. Do you use the thirty mainly for the longer working time or are there other benefits to it?

Just curious about whether i might want to change what I'm using.w
 
I find cracks stay cracks, fill them accentuate them or whatever, you can’t make them disappear, so your best bet is to somehow make them look like natural inclusions most times.

I’ve done the Brass wire stitching in a plate like turning and it worked OK in that piece, but if needed, (but I try and usually succeed to prevent splits) as there are times when the wood itself has some shortcomings that need to be filled, than ground coffee is my usual material to use, tried Epoxy with the materials, but find the restriction of the amount of foreign material that can be added and have it still work not to my liking, especially if one is using something like Copper or Brass powder, where Iwould want to have that material to really show as if it was Copper etc..

So I use the fine coffee grind and pack that solidly into the opening, and then carefully let CA fill the gaps between the ground material, the outcome of that I do like better than the mixed with Epoxy goo
Brass wire stitching.jpg
 
Leo, do you not find if there to be any issues with brittleness using the CA glue? I'm really referring to durability over time. And am I correct in assuming that you use a thin CA glue?
 
I use coffee grounds where it is appropriate to simulate bark or to add to bark that already exists. I wouldn't consider it for the crack in Odie's bowl because there's nothing about the crack that "barks" at me. Occasionally I will mix coffee grounds with medium CA, but usually I will apply a little medium CA and then sprinkle coffee grounds over it. If I know that I will be building a thick layer then I will sprinkle a heavy layer of grounds and then pack it down with thumb pressure. After that sets, I will apply more CA and sprinkles more grounds on top, but maybe just let it set until dry and then blow or vacuum off the loose grounds. This process leaves a rough textured surface that closely matches a bark inclusion. Lightly torching a defect to darken it before adding the coffee is another useful technique.

Finely ground coffee mixed with epoxy closely resembles pith wood. I have used fine tipped touch up pens along with an X-Acto knife and needle to draw wood grain.
 
Mark Hepburn said:
Leo, do you not find if there to be any issues with brittleness using the CA glue? I'm really referring to durability over time. And am I correct in assuming that you use a thin CA glue?
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Yes thin CA usually or add thicker after the initial wetting with the thin CA
As I have used CA starting some years ago, the oldest piece that I (LOML) still have is an 16 year old Apple bowl we have been using daily as our bread bowl, I remember that the log looked abused/rough, and while turning that bowl I found a small thin bend over nail with a string still attached, and it showed bark had been missing and overgrown, as they say it has character, and LOML Anny does like it, it had several splits or rather separations between year rings,
I filled all these places with CA and that bowl and the CA is as solid now as it was 16 years ago.
Old Apple bowl.jpg

I also made a (what we call a floor bowl, as it is too large for a table) from a Willow burl at that time, as it dried the burl clusters opened up, I left it for a couple of years sitting in our living room, and then filled all these splits with coffee ground and CA, so probably only 14 or 15 years old that all looks just fine, after all it doesn’t have anything to do but stay in the wood, there is very little if any movement in the wood

Pictures are from when just filled and from 2 years ago.
Willow burl.jpg

Willow burl 2014.jpg
 
Olaf and Mark:

I now use Permatex twin-tube; previously used Loctite (from HD). Permatex is supposed to have a two-year shelf life, Loctite only one year. I had a long-running argument with Loctite about placement of the date code; it was on the back of the label and couldn't be seen until opening the package. This all began from a failed connection due to very old product. Permatex had it on the flange extending from the package - alas no longer.

I had an unpleasant experience with some 5-minute in a structural application, which never fully hardened - might have also been too old. The 30-minute also gives more working time.

For structural applications, JB Weld is the best I've found; they claim infinite shelf life.
 
Leo Van Der Loo said:
Yes thin CA usually or add thicker after the initial wetting with the thin CA
As I have used CA starting some years ago, the oldest piece that I (LOML) still have is an 16 year old Apple bowl we have been using daily as our bread bowl . . . .
Click to expand...

For years I have heard dire warnings about using CA, but I haven't seen anything that substantiates the claims. I have used it on several medium sized pieces and so far I haven't encountered any problems. However, whether true or not, woodturning lore can have a strong influence on collectors and galleries. Since that is outside my league I sometimes use CA both for repair and as a finish. CA and I have something of a love/hate relationship because every time I use it I manage to get it all over my hands or worse ... my clothing where Mrs B will see it and "gently" remind me of all the things I'm not supposed to do. :D

I do know some of the shortcomings of CA. It's brittle and loves to chip. Coffee grounds helps solve that problem. I done like using it on long thin cracks.

Joe Greiner said:
....I had an unpleasant experience with some 5-minute in a structural application, which never fully hardened - might have also been too old. The 30-minute also gives more working time .....
Click to expand...

I don't like the five minute epoxy because I'm a ten minute woodturner. Also that's not sufficient time for the bubbles to escape.[
 
The CA glue does a nice job of pulling itself into the voids, cracks, splits compared to other
solutions. Starting with the thin on a split and adding medium thickness afterwards the glue
will quickly settle into the voids and you can add additional glue to the crack as it settles. On
some voids it helps to seal the back side of the wood piece if the void runs all the way through
the wall. I will use masking tape to seal one side of the wall or use it to create a dam if the glue
wants to run out in a direction. I have used thin and medium CA glue in a crack and then pushed
fine wood dust into the void and re-applied thin CA over the top, after it dries the repair looks like
a knot depending on the wood type. The dark color woods seem to work best. Turn at a high speed
and clean up with a negative rake tool and then sand and finish.
 
I use quick cure 5 minute epoxy made by System 3 (system3.com) or Woodcraft part number 124270. I love it you can mix whatever in it or just plain ole instant coffee for a dark wood grain effect. I also use it plain with lighter wood area and looks natural. Fills depressions and cracks.
 
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