Forming Fiberglass?

[reef_research]

Hello RC DIY'ers!

I'm looking to set some fiberglass/epoxy in a complicated shape, like that of a rib cage. I was thinking of using metal mesh (like chicken wire) to act as a support frame while it set, but I can't get the detail in need with that method. Next I turned to using a block of styrofoam carved down to get the shape I'm after. The only problem is that I do not know how to keep the epoxy/fiberglass from sticking to the "mold" while it sets. I thought of using wax paper (don't know if that would even work) as an "in between" layer, but don't know if it would conform to the shape of the styrofoam very well. Could the wax paper be boiled a bit until softer, and then allowed to dry over the styrofoam in order to hold the shape?

Any suggestions or experiences?

Thank you,

 

[SoFloReefer]

I am thinking modeling clay with a release (like oil) over it but ive never done it

 

[A.T.T.R]

use styro then i think aceatone to disolve the styro mold

 

[NanoReefWanabe]

for all the car stereo stuff i used to do i always used turtle wax...cover the mold with i and i was always good to go...i usually covered what ever i was forming from with masking tape..

gotta pic of what your trying to mold off of...certain shapes will not release...creating hollow pipe like structures is very hard to do with fiberglass from a mold..all it takes is something to be 1 or 2mm larger in the wrong spot and it is stuck for good...

 

[reef_research]

Hmn, I hadn't thought of dissolving the foam, but I may want to reuse to mold.

The shape is basically like a human ribcage, minus the bones. It's designed to be a cave underneath the sandbed.

Turtle wax....that might work. Where did you attach the masking tape exactly?

 

[inachu]

<a href=showthread.php?s=&postid=13096695#post13096695 target=_blank>Originally posted</a> by SoFloReefer
I am thinking modeling clay with a release (like oil) over it but ive never done it

I think there is a ITUNES video on making a house blast proof using some sort of quick dry resin meant for spraying on the bed of a truck and it forms very nicely.

In this case you could just use styrofoam or wood.

I suggest to go visit a company that sell custom truck lining.

I think the resin they use is tank safe and pretty cheap.

 

[hebygb]

In my sculpture days, we created molds like this all the time... This is the process (keep in mind this is 30 years ago. We created the model in clay... then made a plaster cast of that clay model... As mentioned above, you have to be mindful of undercuts... clay is easy to remove... fiberglass will not allow that flexibility. The plaster cast must be reinforced with cheese cloth. This means many crisscrossing layers as smooth as possible to remove air bubbles... Air bubbles will weaken the mold and prevent reuse.

Now we used a product called poly vinyl chloride to seal the plaster on the mold side.... this creates a really cool thin skin that prevents your first coat of resin from sticking... after several thin coats.... start laying in your fiberglass cloth... once again airbubbles are the enemy.

Now since this is a cave, and I dont think you need precision or detail.... Prbably going to be hidden by rock/sand/coral... you can try this method... Make your basic shape out of clay.... cover in tin foil.... smooth out as best you can... try not to have a lot of folds and seams... start coating in resin and then layering on your glass sheets... I cant emphasize enoughworking as cleanly and carfully as possible. Wear a mask, ventilate the room and be patient... each layer can take a day to cure.

Does this make sense?

 

[reef_research]

Perfectly, thank you. Can anyone recommend a fiberglass/epoxy brand?

 

[8BALL_99]

FWIW I'm like 99.8% sure fiberglass resin will melt Styrofoam

Also, not sure your exact use or shape.. But you could just make it out of ceramic.. Just form the clay then have it fired.. your done..

 

[38bill]

Duct tape works good. You could even wax it to make it release better. You could also apply glue on the form and cover it with plastic kitchen wrap or something similar (easier to form than wax paper). If you have exposed foam on the mold make sure that you don't use a resin that will melt it. For some of the stuff I have made I used foam with plaster over all exposed surfaces and then sealed the plaster with an exterior polyurethane varnish and then waxed the varnish for a good release.

 

[hebygb]

It is true that some styros will melt from resin... and viceversa. I recommend marine resin... afterall many boats and surf boards are styro covered in fiberglass.

Correction to my earlier post... It was called Poly Vinyl Alcohol

 

[NanoReefWanabe]

if you use great stuff foam to make your mold the fiberglass resin wont eat it..

 

[One Dumm Hikk]

<a href=showthread.php?s=&postid=13099483#post13099483 target=_blank>Originally posted</a> by 8BALL_99
FWIW I'm like 99.8% sure fiberglass resin will melt Styrofoam

Also, not sure your exact use or shape.. But you could just make it out of ceramic.. Just form the clay then have it fired.. your done..

Yes, fiberglass resin will melt most styrofoam. The heat it generates when curing is what melts it, not chemically melting it.

Surfboards are sprayed with a layer before fiberglass to prevent the melting effect and it isn't the typical fiberglass they use.

For a potential mold, cut a 5 gallon bucket vertically down the center. Form the cave on the outside, pop the bucket out when done.

 

[NanoReefWanabe]

<a href=showthread.php?s=&postid=13103197#post13103197 target=_blank>Originally posted</a> by One Dumm Hikk
Yes, fiberglass resin will melt most styrofoam. The heat it generates when curing is what melts it, not chemically melting it.

not too sure about that....pretty sure it is a chemical interaction that causes the styro to melt, as it generally melts instantly on contact with the resin...or even magic markers..

the heat will certainly warp and misshape the mold though...

 

[38bill]

The commonly available polyester resin that is used for fiber-glassing will melt most foam even before the hardener is added, its not the heat that does it.

There are several types of resins that can be used for fiber-glassing as well as several types of foam. Epoxy resin should be foam safe and I believe that polyurethane foam may be polyester resin safe. Epoxy resin may be nicer to work with, less smell and shouldn't melt foam, but it may cost a little more.

 

[reef_research]

Alright, so sticking with foam for weight and cost (clay and ceramics, while more permanent, are not feasible for large scale pieces), what do you think of the following?:

Layer 1: Styrofoam insulation (the kind used in building). Used versus regular white styrofoam because its surface holds details better (and there won't be a million foam pellets leftover).

Layer 2: Several coats of polyurethane ("clear coat")

Advantages: Lightweight, cheap, reusable?

Disadvantages?

I was looking into using a food safe polyester resin (no issues with toxicity left to chance) such as this: http://www.tapplastics.com/shop/product.php?pid=9&
Is there any reason to use the food grade for reef tanks, or are resins generally fine after curing?

Also, am I likely to need a releasing agent between the polyurethane and the fiberglass?

Everything is up in the air in terms of brands and such, but I'd like to at least make the purchases by the weekend. The Home Depot sells a 2'x8'x2" foam sheet for about $11, and there is a West Marine store in the local area if HD doesn't have the fiberglass mesh/epoxy/resin.

Thank you,

 

[38bill]

You shouldnt need food grade resin, I think that would be overkill.

West Marine will have the polyester as well as epoxy resin but I find them a little high priced (like full list!) but they do carry hard to find items.

Try the home stores or your local auto part store if you want to use the plain old polyester resin. I buy mine at my local Fleet Farm store in the auto dept, right next to the Bondo.

You will need a release agent no matter what resin you use. You can use paste (car) wax, wipe on some cooking oil or even spray on no-stick cooking spray (its olive oil I believe).

 

[hebygb]

The only problem with a foam core that I can see is that will want to float... big time. You will need to anchor it securely... but be mindful that if you just use LR to hold it down... that this cave will want to launch if there is a tumble, or in a year when you forget, and you start rearranging your tank and lift that last rock... Depending on the size of caves you are looking to make, you could use Large PVC pipe (as is or cut in half) as the internal structure and then just glass over it to your liking.... If you want you can remove the pvc or leave it for added structure... This way you can pile rocks on top all that you wish.

 

[reef_research]

<a href=showthread.php?s=&postid=13113362#post13113362 target=_blank>Originally posted</a> by hebygb
The only problem with a foam core that I can see is that will want to float... big time.

The foam is just for a mold, the fiberglass shell is the only thing going into the tank. Otherwise I'd be guaranteed to have life raft instead of live rock.

Buying materials soon. Will post the results of a test run soon with pics.

Thank you,

 

[reef_research]

Test Run results...

Test Run results...

The resin is still curing, but here are the initial results.

Using the "perimeter insulation" from HD (pink stuff, though color doesn't matter), a 6"x6" test square was cut. On the face, several curves and depressions were added to see if the details would be retained.

Making sure to remove the dust as best as I could, I took a piece of the foam that had been removed from the test square to test the polyurethane on. This was a good thing too, as it turns out that polyurethane will dissolve this type of foam.

Stepping back, I looked for an availible substitute. Wax paper was nowhere to be found, so plastic wrap was used. I do not know yet if the resin dissolved the plastic, but from looking at the underside and edges, I wouldn't say that it has.

The resin was mixed with the hardener to a moderately viscous blend, then applied and smoothed over the fiberglass mesh with a spreader. The test patch is due to cure completely in about an hour, at which time a full overview of the results will be given.

Cross your fingers that all goes well.

As a side note, anyone that doesn't need to keep the mold can just apply a sealant to the face (so porous it would absorb the resin) and then dissolve it with acetone upon the fiberglass shell curing.