CA glue and cracks

[swampgator]

Rather than hijack Ed's wonderful tutorial about building bird boxes

https://forum.shopsmith.com/viewtopic.php?t=10164

and such, I wanted to ask a question about if CA glue would fill in the splits and around the knots. Rather than toss that wood, is it possible and feasible to try to salvage the wood with filler or CA glue? Thanks for your help.

[terrydowning]

I have successfully used thin CA to fill cracks, knots and edges. It even stood up to turning on the lathe. Thin works best for cracks as it can penetrate better. Medium or thick can be used for holding knots in place if the gap is too large for thin.

Just be careful and aware of the defect. I also would not run a plane against said defect, too hard on the edge.

[trainguytom]

CA glue comes in several thicknesses. The standard "super glue" is too thin to even glue wood & is for non-porous items. The thicker varieties will work as a glue & can fill some cracks, but I'm not sure I'd use it that way. I'd probably use it in the cracks to stabilize the wood & hold the knot, but use a different material as a filler. Epoxy makes a better filler, but most are clear, so if you don't want that look, you can color it (I'm told...I've not done that). If you want a wood colored filler, there are a lot of options from plastic wood to sawdust/glue recipes. One of my favorites is Durham's water putty (anyone remember that from junior high wood shop) and tinted with acrylic paint. I use those little bottles from an art supply or hobby shop. If you play a bit, you can match the surrounding wood pretty well. I mix it thick & thin out with the color.

[robinson46176]

I have been building some very "utility" shelves this spring and my wood species is "this and that, white wood" That was on hand.
A number of the pieces while generally plenty solid did have a number of splits in them. I was using some Tite-Bond II to assemble the units along with a some small nails and some screws. I laid the end frames out flat and ran thin beads of that glue on top of each split and left it over night. Most of the little splits filled all the way up and all of them did with a second coat. I'm sure it did not triple the strength of the frames but was functioning on the premise of "it couldn't hurt". Remember that these are fairly rough utility shelves to be sitting out of sight and are not main structral supports for a skyscraper.
They are also NOT soon to be featured in an up-coming issue of Fine Woodworking...


.

[pennview]

If you're referring to checks in the end of a board, it's best to cut them off. They are there because of stresses in the wood and, while you can try CA, they may continue on their merry way at a later date.

But around knots and such, you can fill the void with sanding dust collected from you orbital sander and then add thin CA. Sometimes a CA accelerator spray causes the CA to turn white, so you might want to experiment. If you have large voids or loose knots, mix epoxy with wood dust from the sander or from the table saw, and then pack the mixture into the hole.

[JPG]

If you're referring to checks in the end of a board, it's best to cut them off. They are there because of stresses in the wood and, while you can try CA, they may continue on their merry way at a later date.

But around knots and such, you can fill the void with sanding dust collected from you orbital sander and then add thin CA. Sometimes a CA accelerator spray causes the CA to turn white, so you might want to experiment. If you have large voids or loose knots, mix epoxy with wood dust from the sander or from the table saw, and then pack the mixture into the hole.

I like thin CA for thin cracks/splits since capillary action will force the glue way into the internal end(hopefully). Drying clear allows underlying color to show through small gaps. Works with 'natural' colored finish.

[terrydowning]

Any excess on the surface needs to be dealt with (sanding, scraping, etc.) if staining though. It can leave a "blonde spot" DAMHIKT!

[lightnin]

Building up layers of CA fast...
This should only be done on surfaces to be painted as it is not clear.
put your CA on then sprinkle baking soda on it ... now it's dry.. Like right now...this causes heat also. repeat as necessary.

A friend told me about this it's used by some to fill in dings on airplane propellers. I have not tried it myself. I allays wanted to experiment with it
but never thought of it when I had nothing to do. I seldome have nothing to do.

The last day that I had nothing to do.... well I didn't even get half of it done.

[derekdarling]

Building up layers of CA fast...
This should only be done on surfaces to be painted as it is not clear.
put your CA on then sprinkle baking soda on it ... now it's dry.. Like right now...this causes heat also. repeat as necessary.

A friend told me about this it's used by some to fill in dings on airplane propellers. I have not tried it myself. I allays wanted to experiment with it
but never thought of it when I had nothing to do. I seldome have nothing to do.

Classical guitar players use this same method to buld up and repair fingernails for playing. Works well, but chews the crap out of the fingernails underneath when it bonds.

Derek

[terrydowning]

Building up layers of CA fast...
This should only be done on surfaces to be painted as it is not clear.
put your CA on then sprinkle baking soda on it ... now it's dry.. Like right now...this causes heat also. repeat as necessary.

A friend told me about this it's used by some to fill in dings on airplane propellers. I have not tried it myself. I allays wanted to experiment with it
but never thought of it when I had nothing to do. I seldome have nothing to do.

The last day that I had nothing to do.... well I didn't even get half of it done.

FYI Not all CA is clear, but most is. I know I use it as finish in some of my turning projects. It does build nicely, I have layered to more than 1/32 in at least one instance. and can be polished up to a super glossy, glass like finish.

I use CA finishing techniques on pens, pencils, small bowls, and other small turning projects I want to have a really nice glossy finish. Small is the key here as it is a bit pricey and getting an even application is difficult due to the rapid drying time. Largest bowl I did was 4" and I used a medium CA with no accelerator and still had troubles getting an even application.

As a filler any CA on the wood will prevent other finishing products from absorbing into the wood though. So if filling cracks with it, care must be taken to remove any overburden.