Author Topic: Super fine hair line crack you can feel, not see.  (Read 1640 times)

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Offline Deke

  • Posts: 236
Super fine hair line crack you can feel, not see.
« on: October 12, 2018, 07:23 PM »
This isn't exactly a finishing topic, but I wasn't sure where else it could fit. I made a bent arm Morris chair and one of the arms. right where the sitter will rest their hands, has this annoying super fine crack. I tried taking a picture, but you can't see it. It runs deep, but NOT to the end of the arm. The wood is otherwise pretty solid and there is no way to open the crack even a tiny bit to squirt in some glue, such as CA. I don't want to risk cracking it more. I have sanded this down and you can barely feel it, but I know the wood will move/expand and once again the crack will be felt. Any ideas? Apply some CA or???

Sigh... this is one of those woodworking lessons of fixing a mistake. The chair was a real killer with 70+ little mortises, those bent arms, making the legs... I can't have the thing ruined by feeling that darn crack every time I sit in it. Plus it is the ONLY thing I have made for myself in ten years! Life is not fair! :-)

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Online Svar

  • Posts: 1526
Re: Super fine hair line crack you can feel, not see.
« Reply #1 on: October 12, 2018, 07:32 PM »
Penetrating epoxy will soak in hopefully bonding the crack. There are variety of them for marine applications and for stabilizing rotten wood. You can apply it with a syringe.

Offline HarveyWildes

  • Posts: 792
Re: Super fine hair line crack you can feel, not see.
« Reply #2 on: October 12, 2018, 09:56 PM »
Penetrating epoxy will soak in hopefully bonding the crack. There are variety of them for marine applications and for stabilizing rotten wood. You can apply it with a syringe.

This one gets my vote too.

Offline lwoirhaye

  • Posts: 214
Re: Super fine hair line crack you can feel, not see.
« Reply #3 on: October 13, 2018, 01:12 AM »
Sure.  Try to stabilize the wood underneath with the epoxy.  Guitar repair people know all about this stuff.  Get the wood on the sides of the crack glued together enough so the two sides move together seasonally, then approach the finish.   Scraping and drop filling with super glue is something guitar guys do, followed by buffing.  Guitars tend to be gloss finish though.  The principle still holds.  If you are patient and the repair finish has the same color or lack thereof as the finish around it, enough buffing will reduce any witness lines between the old and new finish so much that nobody will notice.

Offline Deke

  • Posts: 236
Re: Super fine hair line crack you can feel, not see.
« Reply #4 on: October 13, 2018, 08:06 AM »
Thanks everyone! The finish is just Danish oil and wax, so super easy to redo, but am worried about "glossy" epoxy. I actually had some of this stuff I was using on some old rotted window frames, but left it all when we sold that house!

Offline Peter Halle

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  • Posts: 11556
Re: Super fine hair line crack you can feel, not see.
« Reply #5 on: October 13, 2018, 08:16 AM »
If you go the epoxy route, if you can apply a vacuum to the bottom, and controllably “suck” the epoxy into the crack then your finishing concerns might be minimized.  Duct tape and smaller diameter - than your CT hose- tubing might be helpful.

Peter

Offline aloysius

  • Posts: 300
Re: Super fine hair line crack you can feel, not see.
« Reply #6 on: October 13, 2018, 09:07 AM »
This isn't exactly a finishing topic, but I wasn't sure where else it could fit. I made a bent arm Morris chair and one of the arms. right where the sitter will rest their hands, has this annoying super fine crack. I tried taking a picture, but you can't see it. It runs deep, but NOT to the end of the arm. The wood is otherwise pretty solid and there is no way to open the crack even a tiny bit to squirt in some glue, such as CA. I don't want to risk cracking it more. I have sanded this down and you can barely feel it, but I know the wood will move/expand and once again the crack will be felt. Any ideas? Apply some CA or???

Sigh... this is one of those woodworking lessons of fixing a mistake. The chair was a real killer with 70+ little mortises, those bent arms, making the legs... I can't have the thing ruined by feeling that darn crack every time I sit in it. Plus it is the ONLY thing I have made for myself in ten years! Life is not fair! :-)


Here's another possible solution:
http://www.leevalley.com/us/wood/page.aspx?p=30261&cat=1,110,30261
« Last Edit: October 13, 2018, 09:09 AM by aloysius »
FOG-wit since '95:  Some say since birth...

Offline Deke

  • Posts: 236
Re: Super fine hair line crack you can feel, not see.
« Reply #7 on: October 13, 2018, 11:16 AM »
Here's another possible solution:
http://www.leevalley.com/us/wood/page.aspx?p=30261&cat=1,110,30261

Big duh here from me. I actually have this in the shop for another project! I might give it a shot - it is very thin and could penetrate the crack. I really appreciate all the suggestions. My problem is I have no way to access the crack form any other place than the surface. No way I can figure out yet to even separate it a bit to get some kind of glue in there. The arm is well attached to the chair, though I did use hide glue so it is technically reversible, but something I want to avoid for now.

Offline ChuckM

  • Posts: 631
Re: Super fine hair line crack you can feel, not see.
« Reply #8 on: October 13, 2018, 11:54 AM »
Peter's suggestion of using a vac to pull in the glue is a classic one, but if the crack runs only half way into wood, the vac can't do its job.

If the crack is too small for any glue suggestions (penetrating epoxy, low viscosity CA, etc.) to work, I would look into the option of making a small design change:

1) Cut a recess/mortise on the crack area so you can go deep and fix the crack
2) Cover the recess with an inlay. The inlay itself may also work as a fix to hold the split wood together.

The recess can be any shape (butterfly, rectangular, etc.) of your desire, and the inlay to cover it could be wood, a brass plate with your initials, in the shape of a flag of your home country, etc. It is a design opportunity.

A picture or two may help.
« Last Edit: October 13, 2018, 11:57 AM by ChuckM »

Online Svar

  • Posts: 1526
Re: Super fine hair line crack you can feel, not see.
« Reply #9 on: October 13, 2018, 12:17 PM »
Penetrating epoxy will typicaly soak in even without a crack. No need to separate it. Just put some borders and make a puddle. Alternatively you can drill a tiny hole for syringe needle from underneath the arm and pump it in.
Try it on scrap first. Might mess up your finish. God luck.
« Last Edit: October 13, 2018, 12:19 PM by Svar »

Offline Deke

  • Posts: 236
Re: Super fine hair line crack you can feel, not see.
« Reply #10 on: October 13, 2018, 12:20 PM »
Peter's suggestion of using a vac to pull in the glue is a classic one, but if the crack runs only half way into wood, the vac can't do its job.

If the crack is too small for any glue suggestions (penetrating epoxy, low viscosity CA, etc.) to work, I would look into the option of making a small design change:

1) Cut a recess/mortise on the crack area so you can go deep and fix the crack
2) Cover the recess with an inlay. The inlay itself may also work as a fix to hold the split wood together.

The recess can be any shape (butterfly, rectangular, etc.) of your desire, and the inlay to cover it could be wood, a brass plate with your initials, in the shape of a flag of your home country, etc. It is a design opportunity.

A picture or two may help.

Here is a pic. I have considered some kind of design/inlay to cover it, but I really want to avoid that. I'm going to try the soak-in epoxy route first.

Offline Koamolly

  • Posts: 52
Re: Super fine hair line crack you can feel, not see.
« Reply #11 on: October 13, 2018, 12:56 PM »
You might try heating the wood then applying the epoxy.

https://www.epoxycraft.com/thinning-epoxy-best-practice-reducing-viscosity-west-system-epoxy/

From the above link...

Thinning epoxy using heat

“You have two options if you want to thin epoxy using heat. You can heat the resin and hardener components separately and then mix them together to create a thinned epoxy. Or you can heat the substrate – such as wood – and apply your room temperature resin and hardener mix to the heated surface.

A heated mix of resin and hardener does retain all the characteristics of epoxy cured at room temperature – but it cures faster, which might take you by surprise. Using WEST SYSTEM 206 Slow Hardener® or WEST SYSTEM 209 Extra Slow Hardener® can help, as these two hardeners have a slow cure speed giving you more time to work with the warm epoxy.

But if you’re coating wood, the best method is to warm the wood, rather than the epoxy. Remove the heat source just before applying epoxy and the mix will thin as it comes into contact with the wood. As the wood cools, the epoxy is then drawn in deeply before gelling, as the air in the wood fibre contracts.

Whichever method you use, you should be able to comfortably touch the epoxy containers or the wood, so heat them to a maximum of 35˚C. Overheating causes the epoxy to harden too fast. If you see smoke rising from the cured epoxy, it is probably damaged and needs to be replaced.“

Offline ChuckM

  • Posts: 631
Re: Super fine hair line crack you can feel, not see.
« Reply #12 on: October 13, 2018, 01:11 PM »
After looking at the picture, I would say if you are really going to have the inlay approach (i.e. if the glue fix does not work out), you should add the inlay on both arms, not just one. For example, if I were to fix a chair like that, I would add (after the crack fix) two maple leaf inlays to make the fix look like part of the original design.

Good luck with your fix.
« Last Edit: October 13, 2018, 01:14 PM by ChuckM »

Offline ChuckM

  • Posts: 631
Re: Super fine hair line crack you can feel, not see.
« Reply #13 on: October 13, 2018, 01:16 PM »
Penetrating epoxy will typicaly soak in even without a crack. No need to separate it. Just put some borders and make a puddle. Alternatively you can drill a tiny hole for syringe needle from underneath the arm and pump it in.
Try it on scrap first. Might mess up your finish. God luck.
Svar,

Would you consider this a penetrating epoxy?
http://www.leevalley.com/en/wood/page.aspx?p=20013&cat=1,110,42965

If not, does anyone know where we can get penetrating epoxy in Canada?

Online Svar

  • Posts: 1526
Re: Super fine hair line crack you can feel, not see.
« Reply #14 on: October 13, 2018, 01:57 PM »
Svar,
Would you consider this a penetrating epoxy?
http://www.leevalley.com/en/wood/page.aspx?p=20013&cat=1,110,42965
If not, does anyone know where we can get penetrating epoxy in Canada?
I'm not sure. I was thinking something like this:
https://www.jamestowndistributors.com/userportal/show_product.do?pid=97636&familyName=TotalBoat+Penetrating+Epoxy+Kits
I'm sure you can get it in smaller quantities on Amazon or elsewhere. System 3 is a top brand. They are used in wooden boat building to impregnate and waterproof wood. It has consistency of mineral spirit and will go in without creating film on the surface. It's not good for filling voids, but should work for tiny cracks. It is two part epoxy just like all others, but also contains solvent, so it is very slow setting and will decrease in volume when set.
People at Jamestown Distributors are experts on this and may give you an advise.
Again, I'm not sure about it's bonding properties (such as glueing two pieces together), but for preventing the wood from moving, forming cracks, and taking in moisture this is the thing. I.e. hopefully the crack won't open up after treatment.
« Last Edit: October 13, 2018, 02:07 PM by Svar »

Offline Deke

  • Posts: 236
Re: Super fine hair line crack you can feel, not see.
« Reply #15 on: October 14, 2018, 09:49 AM »
Svar,
Would you consider this a penetrating epoxy?
http://www.leevalley.com/en/wood/page.aspx?p=20013&cat=1,110,42965
If not, does anyone know where we can get penetrating epoxy in Canada?
I'm not sure. I was thinking something like this:
https://www.jamestowndistributors.com/userportal/show_product.do?pid=97636&familyName=TotalBoat+Penetrating+Epoxy+Kits
I'm sure you can get it in smaller quantities on Amazon or elsewhere. System 3 is a top brand. They are used in wooden boat building to impregnate and waterproof wood. It has consistency of mineral spirit and will go in without creating film on the surface. It's not good for filling voids, but should work for tiny cracks. It is two part epoxy just like all others, but also contains solvent, so it is very slow setting and will decrease in volume when set.
People at Jamestown Distributors are experts on this and may give you an advise.
Again, I'm not sure about it's bonding properties (such as glueing two pieces together), but for preventing the wood from moving, forming cracks, and taking in moisture this is the thing. I.e. hopefully the crack won't open up after treatment.

I just ordered a pint on Amazon - I had a credit and $30ish doesn't seem too much to spend on a chair that I worked on so hard. I'll let you all know what happens. Thanks!