Friday, January 8, 2016

Lepage PL Premium Construction Adhesive Test

I'm using this construction adhesive to put the boat together (along with coated deck screws).  I'll be using epoxy, however, for plywood lamination and fabric covering.  The joints put together with the PL Premium should never get wet at all although the glue is touted as being waterproof.   I've used it before in house construction and the stuff is tough and strong.  The 825ml big tube goes for $13.50 CDN around here when bought by the tube.  Perhaps a bit cheaper by the case.  One of these tubes goes a long way.

As far as boat building goes though it seems to have an enthusiastic following but is despised in other (I suppose purist) circles. Check out the forums if you are interested in the discourse.  I'm not.

But for the sake of a little fun at the end of the day I thought I would conduct a little test.  It was suggested by someone on a forum that PL Premium has no gap filling qualities and is quite weak when used to bridge a bad joint unlike epoxy.

But I think it would be just as strong in tension as fir plywood is across the grain, and therefore would have excellent gap filling qualities in that regard.  I bet it would laminate plywood just fine.  So here is my little test:

Two scrap pieces of 1/2 inch marine fir plywood.

Some spacers made of floor mat slightly less than 1/8 inch thick.

Spacers at either end.

A bead of PL Premium.

PL Premium squooshed to the thickness of the spacers.  We'll see what happens after it cures.  I bet that when I pry them apart the plywood fibers will tear and the glue will remain intact.  We'll see tomorrow...

In the meantime look at this bulkhead ready to be set up (inverted) to build the hull.  This one is going at the aft end of the cabin where the companionway is.  You can refer to my drawings in the first post to see it in context.  But just walking around it it and imagining the rest of the boat in reference to this has me - and more importantly Lorri - excited about the space we'll have.  That's 10' 6"" interior width for the whole length of the boat!

Okay.  I couldn't leave it alone for the full 24 hour cure.  I glued them up yesterday around 4:30 p.m and it is 10:30 the next morning.  I brought out the instruments of destruction and knocked them apart.

It's plain to see that the Douglas Fir plywood fibers failed and that the PL Premium remained intact.  Armchair experts....sheeesh....

This has got me to thinking about doing all my laminating with PL Premium and saving the epoxy strictly for glassing.


  1. I think that Titebond 3 would be a better option.

  2. Thanks for the reply Tim. I've used Titebond 3 before and like it as well. I haven't done any tests with it though, and I think it needs considerable clamping pressure according to what I hear. You have inspired me to do another test though. I think I will laminate some 1/2 inch fir ply with Titebond 3 without high clamping pressure, and see if the ply tears first. If that is the case I will take your suggestion and use it. It's certainly cleaner to work with!

  3. I use PLp to fill the void where two panels are joined between the inner s&g tape line and the outer line of tape. Put it on a little thick, sand to a nice profile, lay the outside fiberglass and epoxy tape line.
    Basically I use it anywhere thickened epoxy is called for.

  4. I have enjoyed using PL and have even glued up dingy chines with it. But always glassed the exterior. Hard to say how it would do as the primary chine glue with no protection from saltwater intrusion. I wish someone would test George Buehlers supposition that common roofing tar would do for inner layers followed by a exterior treatment of epoxy on cloth. Chris Morejohn uses common fiberglass on his exteriors.... really thickly glassed onto mat and then cloth exterior and has had good results proven over time and hard use. He has written some on this on his blog (chrismorejohn.blogspot more or less). Hard to say if a hardcore budgeteer would do OK with roofing tar lamination and exterior fiberglass with no epoxy at all.

  5. I seriously considered trying the tar lamination thing. It just seemed a bit too scary for a project as large as this considering what the actual saving would be. But I'm going to have lots of scraps to play with and I'll be doing some testing. We'll see what a few years do to some samples. Tar might be all people have down the line...

  6. The product looks very amazing. Hope you had a great experience using it.
    I just found another construction adhesive by Roff. It would be great if you could review the same and let your readers know more about the product.
    Below is the link for the same: construction adhesive