# Does stain weaken a glue joint?



## richgreer (Dec 25, 2009)

Sometimes I like to stain individual pieces before assembly. When i do this some of the gluing surface will get stain on it. My theory is that the stain weakens the holding power of the glue very little and maybe none.

If I ever apply a finish before assembly I always make certain not to put finish on a glue surface - but I think it is okay with respect to stain.

Am I right about this?


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## docholladay (Jan 9, 2010)

Rich, you pose a very interesting question. I would tend to agree with you on a dye or anything that is nothing more than a pigment/color on the wood. As long as it does not seal the wood to prevent glue from being absorbed into the pores of the wood, I would think your hypothesis (my big word or the day) would be correct. I will be interested to watch this post to see if some more learned individuals chime in with real data vs my guesses.

Doc


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## docholladay (Jan 9, 2010)

Rich, one thing does come to mind to counteract your idea. Some stains actually have solid particals that make up the pigment in the stain, in those cases, coloration occurs as a result of those solid particals being absorbed into the pores (filling them) of the wood. I can see how this could afffect glue adhesion. Also, it will depend grealy on what type of carrier/solvent that the pigment is dissolved into. Some are in an agent that would partially seal the wood.

Doc


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## mcase (Oct 31, 2009)

Rich,

I pre-stain and pre-finish most of my work. Its ultimately much quicker and you can evenly polish areas that are usually inaccessible. I never allow stain or finish into areas where there will be glue contact. Its not hard to do. IMO any oil based stain would absolutely effect glue adhesion of any water-based glue. I also recommend pre-finishing. Besides the ease of application there is also the great benefit of being able to wipe away all the glue squeeze out with ease. The glue does not adhere to the finish and wipes off cleanly with a damp paper towel. Of course you can glaze and shade the pre-finished piece after assembly for any desired effect.


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## LeeBarker (Aug 6, 2010)

We're guessing until we test it.

From the same piece of wood, glue three (or six) joints: one of clean wood to clean wood, one with half of one surface stained, one with all of one surface stained. (You could do more with, say, dye.)

Clamp and cure.

While that's going on, devise a way to add incremental, repeatable weight to the joint. There's a beautiful example of this here.

You will learn not only which joint fails first, but also the degree of adhesion where there is contamination.

You'll be the first expert on this question, Rich!


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## Gregn (Mar 26, 2010)

Here is what I got from Titebond's web site.
Can surfaces that have been painted or stained be bonded using Titebond Wood Glues? 
Most of our glues are designed to bond bare wood. Painting or staining a wood blocks the pores, keeping the glue from penetrating into the wood. The Titebond Polyurethane Glue may work for gluing together painted or stained surfaces, but it is necessary to remember that the overall bond will only be as strong as the bond between the paint and the wood. We recommend that all substrates be clean of any type of paint, stain, or sealer.


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## richgreer (Dec 25, 2009)

You guys are great. I'm going to change my practices and avoid staining any surface will be a glue surface just to be on the safe side.

As an FYI - - Yesterday I stained the 22 pieces that make up the 2 plant stands that I am making. However, all my joinery will be dowel pin joinery. I did not drill the necessary holes until after the staining was dry. The real important bond here is the dowel inside the holes and that is all bare wood contact.

b.t.w. - For years I have been buying dowel rods and cutting off my own dowel pins. Today, for the first time, I bought some of those pre-made dowel pins (with the fluted sides). The diameter was dead on accurate (not true with some dowel rods) and the fit was perfect. I would almost say that gluing was optional - but I glued them anyway.


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## stevenhsieh (Jan 8, 2010)

Stain and Dyes will not weaken the glue joint, it is the solvents that manufactor put in their products.


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## stevenhsieh (Jan 8, 2010)

Let me ask you this

What products are you using?


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## a1Jim (Aug 9, 2008)

I say it has to do with what kind of stress is on the glue joint, If you making drawers for small nuts and bolts and pin nail the drawers together ,then I say don't worry about it, the same with face frames that are pocket screwed together.But if your making cabinets that will hold a lot of weight I always tape of the joint before prefinishing. I view it as a similar situation as when your putting a piece of brown paper in glued up pieces of wood so you can pull it apart later ,think of the finish acting like the brown paper being placed between the two pieces you want to stay together. modern glue is much stronger then wood but finish is not.


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## greasemonkeyredneck (Aug 14, 2010)

Someone above said basically that we're whistling dixie until it is tested. Well, this exact thought crossed my mind about a year ago and I did test it. 
I use minwax oil based stains and sometimes waterbased tinted color stains. I tested both the same way and got the same results from both stains.
I used just a basic butt joint.
I glued six identical joints, 
1 gorilla wood glue, no stain
1 titebond, no stain
1 gorilla glue, oil based stain
1 gorilla glue, water based stain
1 titebond, oil based stain
1 titebond, water based stain
I broke all the joint by slinging them on the floor. We are talking simple butt joints on two pieces of wood. They aren't exactly strong to start with. I let everything cure overnight. Then…...
Both joints with just glue held tight, breaking wood around where the glue joint was was.
All four joints that were stained first broke clean. The glue did not hold like it should. Now, they held good enough that if handled with care, I think the joints probably ould have lasted for year. Under stress though, glue does not hold as well as it was meant to.


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## richgreer (Dec 25, 2009)

To respond to Steven H -

The stain in MinWax golden oak. It is their regular stain (not the gel stain).

The glue is Titebond III.


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## gfadvm (Jan 13, 2011)

Oil based stain [like your MinWax] will absolutely prevent Tightbond from properly bonding.The only glue joints I have had fail were wood stained with oil based stain.The type of wood doesnt seem to matter.If you look at the failed joint you can readily see that the glue has not penetrated the wood at all.It was very embarassing when a $400 chair fell apart.


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## stevenhsieh (Jan 8, 2010)

LOOK dyes and pigment have not nothing to do with weakening the joint, it is the products that containing the solvents.
And other consideration is clamping pressure, the way you apply the glue, etc…

A thick layer of glue weakens the joint.
A thin, even layer of glue forms a strong bond.
http://www.provenwoodworking.com/wood-glue.html

How long are you letting the stain dry?


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## stevenhsieh (Jan 8, 2010)

Another good point *gfadvm*
The stain can also prevent the glue from bonding properly.


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## fussy (Jan 18, 2010)

Rich,

I have allways heard that glue is meant on go on bare wood. Oil-based stains-pigment stains-will affect the bond. I too like to prefinish, but I ALLWAYS tape my joints to keep them clean. William's quick and dirty test above adds to that conviction. But, as a1Jim says, if it's a small stress-free part, no worry. By the way, what kind of dowelling jig do you use, and how do you like it?

Steve


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## DMIHOMECENTER (Mar 5, 2011)

The fact that most glues on bare wood will block the staining if you get glue where it doesn't belong tells me a few things. 1) The glue does go into the pores of the wood and is part of the bond. 2) If the stain goes first into a glue area, then it will block the glue from going into the pores, therefore decreasing the strength of the bond.

Solvents are not the problem as long as they flash off before going to any next step (finish or glue). It would be the solids (whether pigments or other) that block the pores. When the solvent flashes (dries) it is gone… as in NOT THERE ANYMORE. If you wipe something on wood and the solvent flashes, then you see something left behind ? There's your solids. Even clear ones (urethane, etc.)

I know, keep and use the gamut of solvents from weak (water, isopropyl alcohol, denatured alcohol) to moderate strength (mineral spirits, lacquer thinner, acetone) to very strong (Xylene, methyl ethyl ketone MEK, carbon tetrachloride, methyl isobutyl ketone MIBK), etc. Every one of these will flash off of wood completely and leave nothing behind. Most will even have a drying effect on the surface and decrease the moisture content at the surface because that moisture flashed off along with the solvent.


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## TopamaxSurvivor (May 2, 2008)

I was gong to suggest a Todd C jiont test, but looks like it is resolved.


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## D_Allen (Oct 11, 2010)

I recently made some rail and stile doors and on the first set there was some areas at the joints that did not take the stain evenly. It was due to some residue of the glue. Even though I tried hard to get it all out of the area with a tweezers and wet sponge. Then I did a test before continuing. I stained both internal sections of a scrap joint. Let it dry overnight and then glued and clamped it. After it dried overnight I tried to break it apart. It is in an 'L' shape and I tried breaking it with a hammer and it would not come apart. I didn't get a bigger hammer and it is still glued together.
In this case there was a lot of glue area and multiple angles of glue surface. I would not recomend that you do this on any glue joint but I have decided that in some cases, such as this, if there is a small amount of stain that gets into a large glue joint then it would not significantly effect the strength. And, it makes staining look a lot better. Mask the area with painters tape but if a small bit of stain gets into the joint….don't sweat it.


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## stevenhsieh (Jan 8, 2010)

Please excuse my ignorance.
I am wrong it is not just the sovents it can be the binder, pigments also.

Best thing to do is not stain where the surface will be glued.


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## RenditionJake (Nov 6, 2015)

This is great! Thanks William for the lab experiment. I now place painters tape along my edges where I plan to apply glue and use a few biscuits to ensure alignment and give a little extra adhesion below the the adjoining stained surfaces. THANKS.


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## shakeshakeshake (Dec 19, 2015)

Gorilla Wood Glue will work on stained surfaces, if you want to stain before assembly. reference gorilla glues website-> http://www.gorillatough.com/node/63

The asthetics of the staining of a piece are way better for me when I stain then assemble, although out of habit I try not to stain surfaces that will not show

Simple thing would be (since you are on the internet) to check your glue makers website for the glue you use


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## unisaw (Jan 31, 2007)

I am making a kitchen cart project for my daughter and it weighs a TON. So i have to fabricate and partially assemble in my basement and then deliver in pieces. This requires that I stain first in my basement shop and then assemble at my daughter's home. Assembly includes gluing trim pieces, some of which are on stained surfaces. I'll research the gorilla glue more. The link above doesn't work BTW.


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## rodneywt1180b (May 5, 2017)

Painter's tape is your friend for keeping your joints clean while pre-finishing.
Water or alcohol based dyes won't affect the strength of your joints.
Oil based stains or any finishes will fill the pores of the wood and will interfere with adhesion. They need to be kept out of your joints.
A liittle stain at the edges of the joint won't affect the strength enough to worry about though.


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## CharlesNeil (Oct 21, 2007)

Short answer, yes it weakens a joint .. as stated above ,, masking tape is your friend


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## CharlesNeil (Oct 21, 2007)

Short answer, yes it weakens a joint .. as stated above ,, masking tape is your friend


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