Better gluing surface: hand-planed or smooth-sanded?

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Forum topic by Brett posted 06-07-2012 10:39 PM 1391 views 0 times favorited 7 replies Add to Favorites Watch
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661 posts in 2888 days

06-07-2012 10:39 PM

Assume you have two boards that have flat surfaces that you wish to glue together. You can either machine-sand the boards with 180-grid sandpaper, or plane them with a well-tuned hand plane. Which surface is better for gluing, the one with a little “tooth” from the sandpaper or the one that is very smooth?

-- More tools, fewer machines.

7 replies so far

View Mark Shymanski's profile

Mark Shymanski

5623 posts in 3918 days

#1 posted 06-07-2012 11:08 PM

An interesting question. Should be easy to rig up a test in the shop.

-- "Checking for square? What madness is this! The cabinet is square because I will it to be so!" Jeremy Greiner LJ Topic#20953 2011 Feb 2

View ITnerd's profile


263 posts in 2805 days

#2 posted 06-07-2012 11:15 PM

Ask, and ye shall recieve –

Net, with Modern glues, assuming good contact & clamping pressure, the wood fibers will usually tear first.

-- Chris @ Atlanta - JGM - Occam's razor tells us that when you hear hoofs, think horses not zebras.

View rockindavan's profile


299 posts in 2841 days

#3 posted 06-07-2012 11:15 PM

Planed, or jointed for sure. The glue doesn’t need any roughness for the glue to work. Glue soaks into the wood and gets its strength from internal bonding. Glue has very little strength to cover gaps such as construction adhesive or epoxy does, so any discrepancy in the surfaces meeting perfectly only weakens the joint.

View bondogaposis's profile


5096 posts in 2556 days

#4 posted 06-07-2012 11:16 PM

I’ll go with the planed surface as providing better wood to wood contact.

-- Bondo Gaposis

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Craftsman on the lake

2833 posts in 3643 days

#5 posted 06-07-2012 11:20 PM

With white or yellow glue the smoother the surface the better the joint should be. So I’d say a good planed joint would be better than 180 grit sanded.

-- The smell of wood, coffee in the cup, the wife let's me do my thing, the lake is peaceful.

View Don W's profile

Don W

19018 posts in 2773 days

#6 posted 06-08-2012 12:53 AM

I would say planed, but either would be stronger than the wood, so both would be Strong enough. Planing however would give a sharper edge thus a less noticeable glue joint.

-- - Collecting is an investment in the past, and the future.

View David Craig's profile

David Craig

2137 posts in 3314 days

#7 posted 06-08-2012 05:32 AM

Glue is absorbed by the wood which is where the strength of the bond lies. Based on that logic, I would say that sandpaper could potentiall fill porous wood with particles that could actually inhibit absorbtion. Of course this is on a very small scale but if we are comparing method to method, this would lead me to believe that a smooth, planed surface would offer better absorption of the glue, therefore a stronger glue joint.

-- There is little that is simple when it comes to making a simple box.

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