" How To" For Epoxy Lamination

[Jay Albrandt]

Hello All,

This site has so much good information on epoxy selection and use, so thank you all who have contributed. If you have experience relevant to my questions, I would so appreciate your input.

I am making new stair treads and risers by laminating 5/16" ash to baltic birch plywood. I think epoxy is the right choice for it's gap filling, shear resistance, strength qualities but I have no experience with it. Other product suggestions are welcome if you feel they would apply. Locally I have access to West System, Total Boat, and System 3.

1. I want to use a slow cure hardener but the temperature in my garage is well out of range. Fast set hardener open time is too intimidating, plus, the overnight temperature is still to low. I like the heating blanket idea I read here but it's not practical in my situation. So, I am thinking of doing the glue ups indoors in a closed up room. Should I be concerned about the off-gassing of the curing process? I would be wearing a respirator during the application.

2. How would you apply it? Roller, paint brush, dump it on and spread with a stick...etc? I have 13 treads at 462 sq. inches (11"x42") and 14 risers at 315 sq. inches (7"x42").
3. Do I need to use an additive or thickener for this process?
4. Some of the baltic pieces have a slight camber and I want to "pull" them straight during the glue up using cauls. I am concerned that too much clamping pressure to achieve this would not be recommended. Thoughts?

Thanks so much for your participation.

Jay

[Andrew Hughes]

Just my curiosity why not make the parts completely out of ash.

[John TenEyck]

I recommend you start with flat pieces of Baltic birch if you want the laminations to come out flat. To do otherwise is asking for trouble.

Also, I would not use 5/16" thick skins. There's no need and it risks creating problems. 3/16" is the maximum I would go, with 1/8" being what commercial stave core stair treads have, IIRC.

There is minimal odor using epoxy; certainly nothing I have ever been concerned about when using it in an enclosed space. I wear gloves and an apron but have never worn a respirator using epoxy. If you can't heat your garage to the minimum temperature recommended, then I would bring it into an indoor room w/o hesitation. I find it best to apply epoxy to the substrate with a notched plastic spreader, using the spread rate listed by the manufacturer. I only apply glue to the substrate.

It's best to do this kind of work with a vacuum bag as it applies consistent, uniform pressure. However, epoxy doesn't need nor benefit from high pressure, so you should be successful using a couple of pieces of plywood on the outside of the veneer and then cauls and clamps.

Good luck,

John

[Kevin Jenness]

I use a roller. A lightly notched trowel will work as well.

Cellulose filler is often recommended for lamination, but as long as it doesn't soak in and leave dry spots straight resin is fine.

Ventilation is a good idea, especially for large quantities. I have never become sensitized to epoxy but it is a possibility you don't want to ignore. Keep it off your skin as well.

As John said, keep the thickness down to 1/8" to avoid checking. Vacuum clamping is ideal if available. If not, use substantial cauls and sufficient clamps for even pressure.
Don't expect to clamp out a bow or twist in the substrate.

Be sure to sand the mating surfaces at 80# for a good bond, if you do that you don't need to worry about over clamping.

Leave a thin layer of epoxy in your mixing cup or on a piece of plastic. Assuming no tension in the layup you can unclamp when the sample can't be dented with your thumbnail.

Don't mix up a big batch and leave it in the mixing container, or it may heat up and kick off in the pot. Do small batches and/or pour into a flat paint tray to slow the exothermic reaction.

It's a lot of work to veneer a staircase worth of material. Unless you have some exceptional material or an unusual design that requires laminated parts, well acclimated solid wood will work fine.

[Jamie Buxton]

I laminate and veneer with West Systems 105. In the winter, I generally use the fast 205 hardener, and leave it in the clamps overnight. In the summer I use the slow 205 hardener, and again usually leave it in the clamps overnight. My shop is unheated and uncooled. I'm in the San Fransisco area, so we're a bit cooler than you in San Diego. Kevin's suggestion for gauging "doneness" is good. You can even do it under a heating blanket by using a baggy.

I use a low-nap roller. You can buy them where you buy the epoxy. Longer nap works too, but leaves more wasted epoxy in the roller at the end of the job.

[mreza Salav]

I have used epoxy (west system) a lot for lamination, in particular for curved stair railing i was doing for our house. It's messy and cleaning is done with alcohol. I would put plastic sheets over the work area to prevent epoxy drops all over. You can use a small roller when it is still thin but it can thicken quickly especially if you make a lot in a pot. Ue no more than 1/8" thick skin. I have never found BB to be flat. Almost all have some cupping.

[andy bessette]

Pick up a copy of "The Gougeon Brothers on Boat Construction." Virtually all you need to know is in that book. Been using WEST System epoxy for over 45 years.

[John TenEyck]

For those that don't know, white vinegar works really well to clean up epoxy squeeze out, etc.

John

[ChrisA Edwards]

Bing! There's my knowledge tip for the day, thanks John..

Got two gallons of this, sitting in a garage cabinet, that the wife had to have during a visit to Costco about a year ago. Now I have a use for it.

[mreza Salav]

For those that don't know, white vinegar works really well to clean up epoxy squeeze out, etc.

John


Yes, that along with Aceton. I prefer alcohol as it's not acidic (that can affect color of some woods) and the smell doesn't linger for long.

[Kevin Jenness]

I find vinegar works best at the early stages post mixing. As the resin cures, alcohol is more effective, then acetone. All of them can leave some staining around joints that may or may not go away. Sometimes the best thing is to prefinish or rub some wax in the corners and come back and pop out minor squeezeout with a chisel, then wash off the wax with solvent

[Richard Coers]

5/16" hardwood acts like hardwood, not veneer. It's going to bow in the spring. You could be a small vacuum bag system and use Titebond for what you will be spending in epoxy. I really don't understand about your concern for gap filling. Do you plan on more than one layer of plywood? I'm a huge advocate of balanced laminations. In my book you need ash on both sides.

[Jamie Buxton]

+1 on Richard's comment. Balanced laminations have the stability you want. Put veneer on both faces.

[Kevin Jenness]

Absolutely, balance the panel. I assumed that was the plan but sometimes the basics are overlooked. The op's area calculations indicate one side only. I am still not clear why the parts need to be laminated in the first place.

[Jay Albrandt]

Hi Andrew,

All the ash and and over half of the baltic birch ply were leftovers from various cabinet projects. Plus, we will be moving this summer and I need to get my shop cleared out. The ash being 4/4 material was resawn and book matched to make up the widths I need. I did look at my options of using solid ash. The lead time on ordering 6/4 material was way too long and it wouldn't have left me enough material to plane and process. 8/4 material would have been such a waste for a 1-1/4" finished thickness. I know this is an unconventional approach but I hope it works out. Thanks for responding.

[Jay Albrandt]

Hi John,

The camber in the baltic is really minimal. I just asked about using the lamination process to "pull" it flat to save some processing after it dries. My thought is that by using 5/16" veeners there is enough material to process them flat once glued together. So, in the end the ash will really only be around 3/16" finished thickness. I think 3/16" plus being epoxied to the baltic should minimize checking. The vacuum bag idea is great, except I am trying to downsize my shop and tools so it would be a one time use thing. It appears that low clamping pressure it the way to go. I have plenty of clamps but unsure how to gauge the appropriate pressure. In your estimation, what would be an appropriate psi if using a vacuum? With your recommendation I will be doing the glue ups indoors. It will solve a bunch of problems for me. Thanks for responding.

[Jay Albrandt]

Kevin,

Thanks for all the good info. I will do some experiments using rollers and a trowel. Also, I never would have thought of sanding with 80 grit. After lamination, the pieces will be processed down so the ash will likely be only 3/16" and if bonded well to the plywood there should be no checking.....hopefully.

[Jay Albrandt]

Andy,

Thanks for the suggestion!

[Jay Albrandt]

Jamie and others,

Correct, the ash will only be laminated to one side of the baltic ply. It will then be glued down using plenty of PL adhesive negating the need to balance the panel. Thank you all for your input.

[Kevin Jenness]

Kevin,

Thanks for all the good info. I will do some experiments using rollers and a trowel. Also, I never would have thought of sanding with 80 grit. After lamination, the pieces will be processed down so the ash will likely be only 3/16" and if bonded well to the plywood there should be no checking.....hopefully.

You may be ok at 3/16", but checking is more likely the thicker the facing is regardless of how well bonded it is to the substrate. 1/8" would be safer. Starting with the thicker material will help with pressure distribution if using cauls and clamps. In a vacuum press I use the maximum pressure available. As long as the surfaces are rough and the spread adequate you will not get a starved joint. If the surfaces are flat there's no reason Titebond wouldn't work; if they aren't flat you need enough pressure to pull the surfaces tight or enough gub to fill the gaps.

[andy bessette]

I simply use a plywood caul with weights on top; cans of nuts and bolts, heavy tool kits, chunks of lead, etc.

[Richard Coers]

Jamie and others,

Correct, the ash will only be laminated to one side of the baltic ply. It will then be glued down using plenty of PL adhesive negating the need to balance the panel. Thank you all for your input.
How does plenty of PL adhesive negate the need for a balancing sheet? Wood won't move in your house? I thought you had plenty of humidity and fog in San Francisco. If it will be more humid in the spring than it will be now, you will have bowing and not splitting. That is if the ash has acclimated to your current moisture level. If it is not acclimated after resawing, then you will get checking, or at the minimum, some open gaps as the ash shrinks. I never hope my work doesn't crack or bow, I follow the rules of nature. 3/16" ash won't straighten anything when glued to a face, especially when applied to only one side with a flexible adhesive.