Replies

1. 
   Sphere | Jul 11, 2009 01:21am | #1

   Well, for one thing, Poly glue is the wrong glue for biscuits. They are compressed beech and the water in PVA and Aliphatic resin glues swell them to fit. Poly won't do that and they stay "sloppy" or relying on a fat glue joint for strength..not good.

   I have used them often on ext. applications and using TB3 or similar water resistant glue that is itself waterbased, is just fine. The glue acts as a barrier from further water intrusion.

   No problems in 2o year old work.

   Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations

   "If Brains was lard, you couldn't grease much of a pan"
   Jed Clampitt

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1. 
   jonblakemore | Jul 11, 2009 05:00am | #4

   Sphere,If you were to wet the surfaces to be glued (including the biscuits) prior to application of poly glue, would that be enough for the biscuits to expand?I did this about 7 years ago with gorilla glue and red cedar. I kept a spray bottle nearby and made sure I had plenty of moisture for the poly to work, according to the instructions. I think it held, but that was 7 years ago and two states away 

   Jon Blakemore RappahannockINC.com Fredericksburg, VA

1. 
   Sphere | Jul 11, 2009 02:07pm | #5

   Maybe. I had a failure that cost me dearly using resorcinol glue ( before there was any advise to wet anything) and also had opened up some work that had poly (gorilla) glue used , I doubt it was pre-wetted, and the foamy stuff was not adding anything to the strength, the biscuit had not filled the slot.

   My take now is using poly may be  worse, think of the expansion pressure behind the biscut, it could force things that don't want to be forced..maybe.

   Sort of like driving a dowel or tennon that is glue locked from no grooves or room for glue, I've seen stuff crack.

   If biscuts are / were meant to use the moiture of the glue to swell, why reinvent the process? Just use water resistant glue, and have a LOT less mess and finger prints on stuff.

   As far as plastic biscuts, the bottle the glue comes in is plastic, and dried glue peels right off...point to ponder.Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations

   "If Brains was lard, you couldn't grease much of a pan"Jed Clampitt

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1. 
   OverKnight | Jul 12, 2009 05:37am | #6

   Thanks, everyone. The reason I'm asking is because I want to build a small bench outside of my backyard shed. I was going to use regular PT deck boards, but I'd first rip the edges square and then biscuit and glue them together. I agree, Sphere, glue doesn't stick to plastic, so I wouldn't consider them an option.

1. 
   Sphere | Jul 12, 2009 01:28pm | #9

   If used for registrating or not meant to be structuallly part of the joint OK. I still prefer TB3 glue over most polys ( the liquid PL premium, is my choice over Gorilla).

   Since i started pocket screwing, my biscut joiner sees a lot less action.

   For what you are doing I often drive a few 3d fin nails in the joint and clip the heads off, leaving a 1/16 or so..dry clamp first and when ya add glue no slippage.Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations

   "If Brains was lard, you couldn't grease much of a pan"Jed Clampitt

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2. 
   BillHartmann | Jul 12, 2009 06:06am | #7

   Where I have seen the plastic biscuits used where for alignment.IIRC they where joining Corian or some thing like that.Not used for strength. And I think that have lightly molded ridges or barbs on them so that they fill the slot width,
   .
   William the Geezer, the sequel to Billy the Kid - Shoe

1. 
   Sphere | Jul 12, 2009 01:22pm | #8

   Yup, BTDT. caution on light color Corian tho', the slot can telegraph.  I tried it once, went back to hot melt glueing blocks and handscrew clamps while the seam fill/epoxy set.Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations

   "If Brains was lard, you couldn't grease much of a pan"Jed Clampitt

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3. 
   frenchy | Jul 12, 2009 03:53pm | #12

   sphere;

   Do you remember abouty a year ago Fine Wood Working tested glues and polyurethane was the weakest glue they tested?  Titebond 111 was the strongest, it's waterproof and also what is recommended for bisquits..

1. 
   Sphere | Jul 12, 2009 04:07pm | #13

   More like 2 years ago..and I don't think they included PL Premium caulk style. That stuff is crazy good.Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations

   "If Brains was lard, you couldn't grease much of a pan"Jed Clampitt

   View Image

2. 
   frenchy | Jul 12, 2009 07:35pm | #14

   I'm sure they didn't because that stuff is more common in house building than fine wood working..   That's what I think is wrong with PL for trim.    It's too gobby.    While it may work well on flooring etc.. I think the thickness of it would throw your measurements slightly off untill you figure out how thick it will be at what temp.  (temp sure seems to affect it's flow rates outta the gun)... It's OK in framing etc. where 1/4 of an inch is normal tolerance but 1/4 of an inch can too easily be seen in trim work.

2. 
   frenchy | Jul 12, 2009 03:51pm | #11

   John, that was the hard and weak way.. Fine Wood Working  tested glues about a year ago and polyurathane glue was the weakest glue they tested.  Titebond 111 was the strongest and it's waterproof plus it's also what they recommend for bisquits..

2. 
   andyfew322 | Jul 11, 2009 01:36am | #2

   I remember a FHB article where the author used some plastic biscuits and gurrilla glue, but I think they made the buiscuits so that they would already fit tightly. ill see if I can find the article

   http://www.cocoboloboy.webs.com
3. 
   Scott | Jul 11, 2009 02:04am | #3

   Lee Valley sells some metal ones that might help you:

   http://www.leevalley.com/hardware/page.aspx?c=1&p=43253cat=3,41306,41319

   Scott.

4. 
   frenchy | Jul 12, 2009 03:48pm | #10

   polyeruthane glue is pretty weak.. Fine Wood Working tested it about a year ago and it was the weakest glue .

    Titebond 111 is the strongest and it's also waterproof.