Author Topic: Foaming Epoxy Additive - supplier?  (Read 4170 times)

Vancouver_foiler

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Re: Foaming Epoxy Additive - supplier?
« Reply #15 on: October 20, 2022, 08:10:02 PM »
Hi Guys,

We regularly mix epoxy resin with polyurethane pour foam and have very good success. The percentage of each is purely a trial and error process. I recommend doing some tests and recording the results. The higher the foam % the weaker the mix. The higher the epoxy the higher the strength. You can also add milled fiber to the mix and get interesting results.

Cheers,
Dave


Dave,

Would you be willing to give us a starting mix to work from?

surfcowboy

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Re: Foaming Epoxy Additive - supplier?
« Reply #16 on: October 23, 2022, 10:01:34 PM »
Man, the fact Dave showed up is enough for me 😆

I'm gonna test some mixes next time I pour foam.

JohnnyTsunami

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Re: Foaming Epoxy Additive - supplier?
« Reply #17 on: November 13, 2022, 11:12:46 PM »
Very interested to know Dave! I'm going to get some 5lb pour foam and test with epoxy.

FYI my application is in doing divinycell board wraps for 1lb foam boards. It seems like the normal weight gain from the D-cell is all in the resin and glass underneath the D-cell and the extra microballons you need to employ to stick it in the rails.

I'd like to do a board with D-cell glued straight to the EPS for most of it. It would mean ding resistance, water proof-ness, once less layer of 6oz carbon needed, and some stiffness for a weight of 2 ounces per side of the board. Granted not as stiff as a sandwich deck but you could do a patch of carbon just under the standing area if you wanted.

Problems with other current options:

- Gorilla glue is too thick and viscous to work with for an entire half of a board.
- Thickened Epoxy is too heavy and doesn't expand at all so you need tons of it.
- PU pour foam is AMAZING but the pot time is 1.5 minutes. I can't get my board in the bag in 1.5 minutes let alone under vacuum.

It would be awesome to put squeegee a thin amount of expanding epoxy onto a blank and slap a shaped D-cell deck on the whole 4' board for less than .5lb so it's still lighter than a 1.5lb blank.

PonoBill

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Re: Foaming Epoxy Additive - supplier?
« Reply #18 on: November 14, 2022, 09:54:45 AM »
Cool idea, though most of the board makers who did a lot of windsurfing stuff have well-developed ways of sticking down D-cell without adding too much weight. Bagging on a layer of table-wet veil before you stick down the d-cell is one technique. If you squeegee out most of the epoxy on the table there isn't much to get into the EPS. You don't want it totally dry because you still want to get enough into the EPS to incorporate the layer. It gives you a true sandwich (composite, d-cell-composite) which is stiff as a girder, and not that great for surfboards (feels dead) but silly stiff is fine for foilboards except probably not so great for Kalama-style Barracudas. Unthickened expoxy on EPS just soaks into the EPS, even if you bag it--or maybe especially if you bag it. I tried it on some car parts and wound up with a nearly dry breather and heavy parts. Lightweight spackle helps with any part that will never have water in it, but if you punch a leaker hole in a surfboard that's been spackled it will delam for sure. I like the idea of epoxy in two-part foam for specific applications. I look forward to trying it, but using it as glue is a non-starter for me. I need long working time to fuck things up and then fix them.

As stiff as a true sandwich can be you probably don't need D-cell on the rails anyway. Especially if you're doing a full carbon or innegra wrap. It's so much easier to just do top and bottom and then taper the edges of the D-cell so you don't get a step, or carve in a deep groove at the edge of the D-cell on the top so the carbon bags down into the groove and gives you a handhold. The structural benefits of a groove is tremendous as well--I learned about that building things out of aluminum sheet. A rolled bead in aluminum sheet looks decorative, but it increases the stiffness of the aluminum hugely. I've made shelf brackets out of .025" that hold 250 pounds easily.
« Last Edit: November 14, 2022, 10:03:12 AM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

JohnnyTsunami

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Re: Foaming Epoxy Additive - supplier?
« Reply #19 on: November 14, 2022, 11:45:58 AM »
Lightweight spackle helps with any part that will never have water in it, but if you punch a leaker hole in a surfboard that's been spackled it will delam for sure.
...
As stiff as a true sandwich can be you probably don't need D-cell on the rails anyway.

I learned the spackle and finishing lesson the hard way. My first board I posted in a thread here is now sitting in the yard, super soft everywhere, 2lbs heavier. I'm throwing out the water soluble spackle, haha.

My last board was full D-cell and I love not worrying about little leaks or cracks, but I want it lighter. I.e. glassing carbon on the board in a bag to extract the extra resin, then putting the Dcell on with ultralight foaming epoxy and saving 1/2 pound per side, or doing it together after a perfect mix on a wetout table (a bit tricky in a tight space).

I'm trying to do the math and it's impossible without running a bunch of tests on whether, say 3 layers of 6oz carbon on rails is enough on bare 1lb EPS, or 2 layers of 6oz carbon with Dcell in between is better, or if D cell with two layers of carbon on top, etc.

The issue, as I see it, is that Dcell would be perfect if I had a better way/lighter way to glue it without voids.

Bert, in old swaylocks threads hints that he uses a foaming trick to glue laminates but doesn't go into it. I'm thinking it's foaming epoxy or mixing the PU and epoxy to different amounts.

PonoBill

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Re: Foaming Epoxy Additive - supplier?
« Reply #20 on: November 14, 2022, 12:15:56 PM »
If you glass carbon directly on EPS you won't extract much epoxy--most of it will just get pushed into the EPS, with not a lot of value other than better incorporation of the first layer. 6oz Carbon holds a hell of a lot of epoxy even if it's squeegeed on a table. That epoxy doesn't go through the peel ply in any significant volume. You might as well use a barrier layer instead and save the peel ply and breather. If I do that I just use Kirkland paper towels as the breather. Table wet 1oz glass doesn't hold a lot of epoxy, so bagging it on yields roughly the same weight gain as spackle without that pesky water-soluble issue. Some folks use epoxy and micro balloons or other thickeners, but it adds a lot of weight and no strength.  Even wimpy 1oz glass under D-cell with carbon as the outer layer creates a girder effect that adds strength with the benefit of not shoving much epoxy into the EPS. Make up a few test pieces and break them. You'll be amazed. There's the added benefit that anyone can shape 1oz around even the nastiest corners. No spring back--it stays where you put it. Do use peel ply if you do this to give a nice rough surface for the D-cell to get glued to. I'm lazy so I do this in one step: table wet 1oz lightly squeegeed, D-cell, then bag with just a breather or use peelply to prevent a mess of breather stuck to the edges.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

JohnnyTsunami

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Re: Foaming Epoxy Additive - supplier?
« Reply #21 on: November 14, 2022, 03:29:12 PM »
Tcomposites dot com has Sicomin foaming epoxy.

They have Sicomin PB 170 (10lb/ft3) and 250 (15lb.ft3). It comes in 6.55kg kit for about $200. The B 170 is a special order and the lead time is 12 to 14 weeks.

I figure 250 kg/m3 density is 1/5th the density of epoxy so this would still be almost half the weight of thickened epoxy say 3:1 by volume with microballoons. The 170 would be more than twice as light as thickened epoxy.

Ideally there would be 5lb or even 2lb since it wouldn't help to have anything stronger than the things you are glueing together, but it doesn't seem like that exists.

Hard to say if it's worth it to have another product in the shaping room. Maybe I just need more practice on the rails laminating D-cell.

tarquin

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Re: Foaming Epoxy Additive - supplier?
« Reply #22 on: November 17, 2022, 10:32:31 PM »
Very interested to know Dave! I'm going to get some 5lb pour foam and test with epoxy.

FYI my application is in doing divinycell board wraps for 1lb foam boards. It seems like the normal weight gain from the D-cell is all in the resin and glass underneath the D-cell and the extra microballons you need to employ to stick it in the rails.

I'd like to do a board with D-cell glued straight to the EPS for most of it. It would mean ding resistance, water proof-ness, once less layer of 6oz carbon needed, and some stiffness for a weight of 2 ounces per side of the board. Granted not as stiff as a sandwich deck but you could do a patch of carbon just under the standing area if you wanted.

Problems with other current options:

- Gorilla glue is too thick and viscous to work with for an entire half of a board.
- Thickened Epoxy is too heavy and doesn't expand at all so you need tons of it.
- PU pour foam is AMAZING but the pot time is 1.5 minutes. I can't get my board in the bag in 1.5 minutes let alone under vacuum.

It would be awesome to put squeegee a thin amount of expanding epoxy onto a blank and slap a shaped D-cell deck on the whole 4' board for less than .5lb so it's still lighter than a 1.5lb blank.

 PU glue can be very different. Don't know if you can get different brands, but try a different brand.
 I learnt a lot from Grant Newby. EPS blank with Paulownia side walls to keep the rocker. Then high density foam vac bagged on with PU glue.

 


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