XPS and Epoxy

Canvas covered foamies (Thrifty Alternatives...)

Moderator: eaglesdare

Re: XPS and Epoxy

Postby kstills » Fri Jan 27, 2023 7:10 am

Impact resistance of front and back of the panel. I beat on this thing with a channel locks.


The front of the panel will 'spiderweb' when you hit it 'gently', a consequence of the thicker layer of epoxy on the panel. This shouldn't be a problem as the paint will hide the spiderwebbing.

IMG_0717.jpg
IMG_0717.jpg (22.04 KiB) Viewed 643 times


The front of the panel will definitely deform from a solid hit.

IMG_0716.jpg
IMG_0716.jpg (25.41 KiB) Viewed 643 times




The back of the panel does not.

IMG_0715.jpg
IMG_0715.jpg (22.99 KiB) Viewed 643 times
kstills
Teardrop Builder
 
Posts: 34
Joined: Wed Dec 21, 2022 10:23 am

Re: XPS and Epoxy

Postby kstills » Fri Jan 27, 2023 7:13 am

I'm not sure I have the best epoxy for this build, I bought sample bottles of 'table top' epoxy off Amazon for this test because they advertised 72 hour cure. I'm going to get some from the countertop guys and give this another try. Primarily because after all was said and done, the adhesion pretty much sucked. Again, it's probably good enough for interior, non structural work, but why accept poor adhesion if I can get better with another brand?
kstills
Teardrop Builder
 
Posts: 34
Joined: Wed Dec 21, 2022 10:23 am

Re: XPS and Epoxy

Postby Pmullen503 » Fri Jan 27, 2023 8:34 am

Personally I like either Raka or System 3 low viscosity, non blushing resins. When I need a really clear lay up over wood that is going to show.

To save some money try US Composites or Total Boat. I've used both for molded parts mostly and they are fine.

I started 30 years ago with West System and its a great product but a little over priced. I still use small amounts occasionally because I can get it locally. They have a good assortment of epoxy additives.

I would not use table top or casting epoxy for fiberglass work.
Pmullen503
1000 Club
1000 Club
 
Posts: 1103
Images: 67
Joined: Sun Nov 23, 2014 1:33 pm
Location: Fond du Lac, WI
Top

Re: XPS and Epoxy

Postby kstills » Fri Jan 27, 2023 8:38 am

Pmullen503 wrote:Personally I like either Raka or System 3 low viscosity, non blushing resins. When I need a really clear lay up over wood that is going to show.

To save some money try US Composites or Total Boat. I've used both for molded parts mostly and they are fine.

I started 30 years ago with West System and its a great product but a little over priced. I still use small amounts occasionally because I can get it locally. They have a good assortment of epoxy additives.

I would not use table top or casting epoxy for fiberglass work.


This.
kstills
Teardrop Builder
 
Posts: 34
Joined: Wed Dec 21, 2022 10:23 am
Top

Re: XPS and Epoxy

Postby Pmullen503 » Fri Jan 27, 2023 8:51 am

There is no such thing as 5 minute or 72 hour cure epoxy; it is entirely dependant on temperature.

Usually epoxies are sold by slow medium and fast cure times. The resin is typically the same just the "part B" is different.

Don't get the fast hardener unless you know you shop will be below 60F. Medium is usually best for most beginners unless you work at 75F or above then go with slow.

I once tried to use some slow cure at around 50F and it took a week to gel and didn't fully harden for weeks.
Pmullen503
1000 Club
1000 Club
 
Posts: 1103
Images: 67
Joined: Sun Nov 23, 2014 1:33 pm
Location: Fond du Lac, WI
Top

Re: XPS and Epoxy

Postby kstills » Fri Jan 27, 2023 9:44 am

Pmullen503 wrote:There is no such thing as 5 minute or 72 hour cure epoxy; it is entirely dependant on temperature.

Usually epoxies are sold by slow medium and fast cure times. The resin is typically the same just the "part B" is different.

Don't get the fast hardener unless you know you shop will be below 60F. Medium is usually best for most beginners unless you work at 75F or above then go with slow.

I once tried to use some slow cure at around 50F and it took a week to gel and didn't fully harden for weeks.



:thumbsup:
kstills
Teardrop Builder
 
Posts: 34
Joined: Wed Dec 21, 2022 10:23 am
Top

Re: XPS and Epoxy

Postby jakejakejake » Fri Jan 27, 2023 1:05 pm

I second using uscomposites, west systems, total boat or any other manufacturer of low viscosity resins designed for composite repair/construction. As stated above West Systems is great but pricey. I find little difference in the epoxy available through uscomposites and West Systems.

Something else to bring up. Excess epoxy provides no additional strength to a part, only weight.

kstills wrote: The front of the panel will 'spiderweb' when you hit it 'gently', a consequence of the thicker layer of epoxy on the panel. This shouldn't be a problem as the paint will hide the spiderwebbing.


That "spiderwebbing" is a path for water into and behind your fiberglass and will lead to a failure of the assembly.
User avatar
jakejakejake
Teardrop Advisor
 
Posts: 62
Images: 24
Joined: Sat Jul 02, 2022 4:44 pm
Location: Texas
Top

Re: XPS and Epoxy

Postby fonsan » Fri Jan 27, 2023 2:10 pm

kstills wrote:Impact resistance of front and back of the panel. I beat on this thing with a channel locks.


The front of the panel will 'spiderweb' when you hit it 'gently', a consequence of the thicker layer of epoxy on the panel. This shouldn't be a problem as the paint will hide the spiderwebbing.

IMG_0717.jpg


The front of the panel will definitely deform from a solid hit.

IMG_0716.jpg




The back of the panel does not.

IMG_0715.jpg


You mention that the back of the panel is 6oz, for clarification what weight are you using on the front?
fonsan
Teardrop Inspector
 
Posts: 18
Joined: Sun Jan 22, 2023 6:38 pm
Top

Re: XPS and Epoxy

Postby tony.latham » Fri Jan 27, 2023 3:10 pm

I would not use table top or casting epoxy for fiberglass work.


I second that. If the ratio of epoxy to fiberglass is high, it will crack if flexed.

Me? I'm a Raka guy.

Tony
User avatar
tony.latham
Gold Donating Member
 
Posts: 6880
Images: 17
Joined: Mon Jul 08, 2013 4:03 pm
Location: Middle of Idaho on the edge of nowhere
Top

Re: XPS and Epoxy

Postby fonsan » Fri Jan 27, 2023 5:14 pm

More testing found on the tube.

Note that he does not sand the xps before hand which has been demonstrated to half the adherence strength

https://www.youtube.com/watch?v=RoztBhIRtv4
fonsan
Teardrop Inspector
 
Posts: 18
Joined: Sun Jan 22, 2023 6:38 pm
Top

Re: XPS and Epoxy

Postby ghcoe » Sat Jan 28, 2023 10:41 am

I think my PMF comes out quite good. If you find the right canvas. They make some really tight weave canvas. I have used 10oz drop cloths and purchased 10oz tight weave duck. It just depends on the look you want.

20210511_164833 s.jpg
Smooth
20210511_164833 s.jpg (440.71 KiB) Viewed 485 times


Nice thing about PMF is that if it does take a hit, it will not shatter, but will absorb the impact in the localized area. It will not try to spread the impact to the rest of the structure. Here are some pictures of a deer hit at 60mph on #3.

20200718_202742 s.jpg
Deer hit #1
20200718_202742 s.jpg (125.21 KiB) Viewed 485 times


20200718_202750 s.jpg
Deer hit #2
20200718_202750 s.jpg (121.59 KiB) Viewed 485 times
George.

Gorrilla Glue, Great Stuff and Gripper. The three G's of foamie construction.

My build viewtopic.php?t=54099
Working with flashing for foamie construction viewtopic.php?f=55&t=60303
Making a hot wire http://tnttt.com/viewtopic.php?f=55&t=55323
User avatar
ghcoe
1000 Club
1000 Club
 
Posts: 1938
Joined: Fri Dec 11, 2009 11:20 pm
Location: SW Idaho
Top

Re: XPS and Epoxy

Postby ghcoe » Sat Jan 28, 2023 10:43 am

If that would have been fiberglass it would have shattered and delaminated.

20200718_202921 s.jpg
Deer hit #3
20200718_202921 s.jpg (73.42 KiB) Viewed 485 times
George.

Gorrilla Glue, Great Stuff and Gripper. The three G's of foamie construction.

My build viewtopic.php?t=54099
Working with flashing for foamie construction viewtopic.php?f=55&t=60303
Making a hot wire http://tnttt.com/viewtopic.php?f=55&t=55323
User avatar
ghcoe
1000 Club
1000 Club
 
Posts: 1938
Joined: Fri Dec 11, 2009 11:20 pm
Location: SW Idaho
Top

Re: XPS and Epoxy

Postby tomhawk » Sat Jan 28, 2023 11:39 am

George, that is amazing that you have had those hits!
I have not yet collided with a deer with my build:

viewtopic.php?f=55&t=75248

Some time ago my colleague was killed when a deer went through her car windshield at 60 mph.
I am thinking deer are far more dangerous than grizzly bears.

Tom
Evolution is driven by mistakes, not plans.

My build: https://www.tnttt.com/viewtopic.php?f=55&t=75248
User avatar
tomhawk
Teardrop Advisor
 
Posts: 92
Images: 99
Joined: Fri Dec 29, 2017 11:51 am
Location: Eastern Iowa
Top

Re: XPS and Epoxy

Postby ghcoe » Sat Jan 28, 2023 6:01 pm

tomhawk wrote:George, that is amazing that you have had those hits!
I have not yet collided with a deer with my build:

viewtopic.php?f=55&t=75248

Some time ago my colleague was killed when a deer went through her car windshield at 60 mph.
I am thinking deer are far more dangerous than grizzly bears.

Tom


Let's hope you never do find a deer like that. This guy said he does not really know how he missed it with his truck, but it hit the trailer square. Said he saw an antler flying and the deer spinning in the roadway behind him when he looked into his side mirror. Really too bad, he had not even had a chance to use it yet. The good news was that he said on the inside there was no damage.

I had a full 5 gallon Jerry can fall off my Jeep on one trip. I felt the impact physically inside the Jeep it hit so hard. At that point I did not know what it was till my trail companion said something just fell off your Jeep over the CB and it looked like a Jerry can. After hearing that I had dread to see how much damage the trailer had taken. The Jerry can had pushed the corner edge back about a 1". I was quite surprised by how much impact I felt through Jeep. By time we got done with the trip it had almost healed itself. Now, 3 years later, you can hardly even tell where the impact was. It would been a lot worse if it was fiberglassed. Fiberglass does not heal itself...
George.

Gorrilla Glue, Great Stuff and Gripper. The three G's of foamie construction.

My build viewtopic.php?t=54099
Working with flashing for foamie construction viewtopic.php?f=55&t=60303
Making a hot wire http://tnttt.com/viewtopic.php?f=55&t=55323
User avatar
ghcoe
1000 Club
1000 Club
 
Posts: 1938
Joined: Fri Dec 11, 2009 11:20 pm
Location: SW Idaho
Top

Re: XPS and Epoxy

Postby woodie72 » Sat Jan 28, 2023 6:16 pm

fonsan wrote:

The thinnest wood i can get a hold of where I am (EU) is 3 mm ply wood for about 9 euro/usd. Presuming having to do both faces of a composite panel it would end up being 2oz cloth with epoxy, 3mm plywood, epoxy, xps foam, epoxy, 3mm plywood, 2oz cloth epoxy

This would more than double the cost and work per sqm and it seems to me that the more elegant solution is just to chose a heavier cloth instead of adding plywood to the mix. I am getting the feeling that 2-4oz cloth might be sufficient in terms of surface resistance as I don't really mind repairing any damage.

I am starting to realise that what I am asking about is the rigidity of the structure and not the surface resistance to damage as it seems that the rigidity will dictate the thickness of the fiberglass cloth


I don't know from which country you are in Europe, but there's birch ply ranging from 0.4mm to 2.5mm. It's In 0.2mm increments up to 1.2mm, 1.5mm, 2mm and 2,5mm is available. Costs a penny, but it's available. Must be available in more countries in Europe.
https://www.intriplex.nl/plaatmateriaal/multiplex/berken/?p=2
woodie72
Teardrop Builder
 
Posts: 42
Images: 15
Joined: Sun Jan 12, 2020 6:03 am
Top

PreviousNext

Return to Foamies

Who is online

Users browsing this forum: No registered users and 10 guests