People seem to be over critical of your experiment. I think your video is great. It allows people to get a sense of how strong foam can be with different coverings.

@kimdonaghyrealtor8238

4 ай бұрын

Yup. Thanks. I am considering doing another video at some time to show different methods of glueing the fabrics to the foam. I doubt that will have any impact on the bending strength because the fabric will still fail at the same tensile strength, but it would be interesting to see.

I saw a guy use polyethylene landscape fabric with good results. The key is the multi-layer approach which puts one outer layer in tension and the other outer layer in compression. Using resin provides much more rigidity than primer, paint, or wood glue. Cedar strip canoes typically use 1/4" thick x 3/4" wide cedar strips with fiberglass cloth and resin on both exterior surfaces and the finished construction is quite rugged. Spar varnish is required to protect the resin from uv radiation.

@kimdonaghyrealtor8238

2 ай бұрын

Very good points. I like the long term durability of the epoxy too. I built a cedar canoe a few years ago and did a video series for that too. Planning to build another soon.

Great very basic tests! I think had you poked some holes (even shallow ones) into the foam board and then put primer on all sides (edges included), then the cotton material (or even window screen material), I think it would have been even stronger. Just a theory here, but makes sense in my head. Thanks again for the fun video and hope your project turned out well!

@kimdonaghyrealtor8238

17 күн бұрын

Thanks. The choice of fabric really makes the biggest difference. Using canvas or screen like you mentioned will greatly improve the bending strength.

It might not have all the metrics people look for engineering purposes, but tests like these offer a good intuitive understanding of material properties. Thanks for this vid. :)

@kimdonaghyrealtor8238

3 ай бұрын

Thanks!

Thank you for this comparison. I hadn't seen a video directly comparing PMF to fiberglassed foam. I am planning a teardrop camper build and I was thinking of making mine out of DIY composite panels. The panels would be made with 3mm Okoume/2" foam/3mm Okoume, fiberglassed on both sides. After seeing this video I'm wondering if the Okoume is even necessary for the extra rigidity. I keep going back and forth on using the Okoume or not because although it will add rigidity (and beauty) to the camper it also opens the door for potential wood rot.

@kimdonaghyrealtor8238

10 ай бұрын

I would probably make a small test panel and see how you like it.

The PMF would have done better if you had used the glue. You have to use titebond 2 glue and let it dry before you paint it.

@kimdonaghyrealtor8238

Жыл бұрын

Makes sense. We are still limited by the tensile strength of the foam. The best glue in the world will not help us there :)

Perhaps it's worth trying out PMF based on thin plywood.

@kimdonaghyrealtor8238

2 ай бұрын

It could work but PMF is subject to leaks and small cracks. I would be concerned about the wood eventually rotting.

So how would this have worked out using the epoxy with the linen? And would using linen save $$$ over the Fiberglass mesh?

@kimdonaghyrealtor8238

8 ай бұрын

The fiberglass cloth adds significant strength to the system but also adds significant cost. The epoxy is really only there to hold everything rigidly in place. You could use epoxy with linen for a harder finish than but you would not gain much strength. The epoxy would also help to make it more waterproof than the paint.

Love it I am in the process of trying to build a slide in camper for my truck and using foam and fiberglass

@kimdonaghyrealtor8238

Ай бұрын

I hope it turns out great!

@xaploq1

Ай бұрын

@@kimdonaghyrealtor8238 was thinking of putting wood for the load bearing base. And then interlock the foam similiar to another youtuber

@kimdonaghyrealtor8238

Ай бұрын

@@xaploq1 yes. You definitely need something rigid to support the bottom. I used PVC boards just in case I ever have water contact. I don't want rot.

@xaploq1

Ай бұрын

@kimdonaghyrealtor8238 never thought of the rot but would the resin at least seal the wood if I were to just use that as a sealer or encapsulate the whole base with resin and fiberglass

@kimdonaghyrealtor8238

Ай бұрын

@@xaploq1 the resin should seal it, but I am just nervous that it might crack and let water in eventually.

With PMF, you really need 2 dropcloths made from canvas and titebond 2 with a layer of paint on the exterior, also when trying to carry weight (camper floor) you want to block out the design as the foam is still foam (I'd use a double 2 pieces 1/2" foam with two layers of canvas on it and then some 3 inch pieces of half inch foam wrapped in canvas glued upright between them to add weight strength). Basically a set of PMF joists glued between a PMF floor and PMF base/foundation.

@kimdonaghyrealtor8238

7 ай бұрын

Yes. You can definitely make both systems stronger by modifying the shapes. Even so, we are always limited by the crush strength of the foam.

Interesting results! Seems the compression strength of epoxy and fiberglass is what makes the difference? Neither outside, which is in tension, failed. Titebond 3 might have had better compression strength, but a lot of people seem to be using paint so I'd say this qualifies as poor mans fiberglass. In the comments you mention that foam crushes easily - but that's true for both fiberglass and cloth. More experiments would be required. Fiberglass and expoxy on one side and PMF on the other and test them both ways would be interesting to see, if anyone wants to give it a go...

@kimdonaghyrealtor8238

2 ай бұрын

The epoxy definitely adds rigidity. Much more than Titebond or paint would. They make a higher compression strength foam but it is harder to find.

Yes, you finally mentioned glue for PMF but on TOP of using the glue, if you use a perforation roller on the foam, then brush on the glue, then lay the material, let it dry, add another layer of glue, let dry and then paint with any good acrylic paint at least 2-3 layers (if you like, sand between each to get a smooth finish), THEN you actually have the PMF to put up against resin and fiberglass. Just saying!

@kimdonaghyrealtor8238

2 ай бұрын

I think that would definitely help, but I don't think the Titebond glue and fabric will ever have the same strength and rigidity as epoxy and fiberglass will.

Poor mans fiber glass is great for someone who is poor like me lmao

I was curious what a snowload would be bc I dont have a garage . Building one of those would negate poormans fiberglass 😂

@kimdonaghyrealtor8238

2 ай бұрын

I never did any engineering calculations on the strength, but I would not hesitate to sit on top. My little teardrop is really strong. Snow would not be a problem at all with the fiberglass system I used. Not sure about the PMF.

@Ketch22k

2 ай бұрын

@kimdonaghyrealtor8238 I was leary about the poorman without a garage but glad I came across your video. Closest i found to an answer. Definitely fiberglass or something else without good storage

@kimdonaghyrealtor8238

2 ай бұрын

@@Ketch22k agreed. I have seen a lot of PMF where they tore it off after 2 years because everything underneath was rotten. Good luck on your build.

I thought poor mans fiberglass was glue not primer. I am confused.

@kimdonaghyrealtor8238

3 ай бұрын

It can really be anything that sticks the fabric to the foam. I found that primer sticks better than wood glue. You should test that and let me know. I would love to see the results.

@EagleRue

3 ай бұрын

@@kimdonaghyrealtor8238 we just bought some stuff to test this week!

@marlaplunk2833

Ай бұрын

@@EagleRue Did you do the test?

You did not make the poor man's fiberglass a fair chance because you did it wrong you're not supposed to use paint as a bonding agent tidond 3 is what you should have been using

@kimdonaghyrealtor8238

6 ай бұрын

I was actually impressed by how well it did with just the paint. I'm not sure adding a layer of wood glue would make a significant difference in the compressive strength, though. The fiberglass does better because of the rigidity of the skin. Cotton cloth just isn't as strong as fiberglass.

@frankbowman22

6 ай бұрын

@@kimdonaghyrealtor8238 I repeat what I said you did not give it a fair trial if you did you would see that the glue is far superior than the paint that you used

@kimdonaghyrealtor8238

6 ай бұрын

@@frankbowman22 You should make a video to compare the way you want so we can see how much difference it makes. I would love to see the difference.

@frankbowman22

6 ай бұрын

@@kimdonaghyrealtor8238 this is the last comment I'm going to make to you about this subject because you are so narrow-minded you can't look at the dozens of videos that's already out there and you want me to prove and back up what I'm saying I don't have to because there's dozens of videos out there that already back up what I'm saying you are the one who is responsible to back up what you're saying exactly