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FIberglass Mold How to Tutorial

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Old 11-12-2007, 12:01 PM
  #1
DocJones199
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Default FIberglass Mold How to Tutorial

I have been asked so often over the years about how I make models out of fiberglass. Since there seems to be such great interest, I have decided to start this thread to show the process. Please comment and make suggestions. Although I have been working with fiberglass and building models for over 30 years, there is always new stuff to learn. With that, here I go.

I have made many things out of fiberglass over the years. Typically, my projects involve building a plug, making a mold from that plug and finally using that mold to make pieces.

One project that I have wanted to do for a while was inspired by a ceiling fan that I first saw years ago. I am sure that you have seen the fans that look like the nose of a WW II fighter plane. From the moment that I saw that fan, I thought that it would be cool to have a helicopter body that would hang from the underside of the ceiling fan making the fan blades look like rotor blades. Of course the helicopter would have to be a classic – I chose the UH-1 from the Vietnam era.

Thus the project begins. The first thing I like to do when I am building something like this is to go to the hobby store and pick up a model of the helicopter that I want to build. I use this model as a three dimensional reference. While 3D references are not always available, I do like to use them when possible. For this project, I selected a 1/35 scale UH-1. Using this model, I can get a good idea of the size that the fuselage has to be relative to the diameter of the fan blades in order to maintain a scale appearance.

I began to build the fuselage of the model and began to analyze the proportions, angles and curves of the copter. See the photo of the fuselage below.


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>

At this point, I can begin to produce profile drawings of the copter. I definitely need to start with a view from the top and a view from the side.
Some of this is accomplished through artistic ability and some of it is cheating. The model that I bought had these views in the painting instructions. Based on the diameter of the fan blades, I figured that the fuselage should be about 40 inches from nose to tail. I simply used my copier to blow these views up to the size that I need. Then I drew in some details that were lost in the enlarging process. See the photos below.


The next step for me was to trace these profiles onto a base that I can use to build a plug. I like to use 1/8 inch mahogany door skin for this. I like mahogany because I can buy it at home depot for cheap and one sheet is more than enough material for a project like this. In the photos below you can see the cut outs that I did in the door skin.


You can see that they warp a little. This warping is no big deal since I will easily straighten the pieces out during assembly of the frame. Next, I want to decide along which line to epoxy the primary horizontal shape to the vertical shape. Having access to my plastic model makes this decision easy. In the photos below you can see how I glue two pieces like these. Angle aluminum stock is easy to clamp the pieces to and assures reasonable alignment of the parts.

In addition to angle aluminum making alignment of not so straight pieces easier, it also gives a pretty good 90 degree alignment of one piece to the other.

At this point I need to make a statement concerning scale. I am no artist, I know from the outset of a project like this that when I am done, anyone who knows anything about helicopters is going to look at this and say “Hey, that’s a Huey UH-1”. That is good enough for me. You can put as much talent and time as you wish into a project. This is your prerogative. I like to get a project’s detail to the point where I am satisfied. I think that I am usually satisfied with my projects bearing a close resemblance to the vision that I started with. That being said, nothing that I ever build will ever be completely scale (unless I happen to trip over a bucket of talent and patience). That is all I have to say about that.
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Old 11-12-2007, 02:05 PM
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Default RE: FIberglass Mold How to Tutorial

Looking forward to seeing more installments on this. I would like to see the basics on how you get the mold all set up and to the point where you can pop out a part. It would be nice to be able to make my own canopy (not scale just a reproduction of the original).
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Old 11-12-2007, 03:38 PM
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DocJones199
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Default RE: FIberglass Mold How to Tutorial

This will definitely get you there. Thanks for your interest, fiberglass is a great material to work with.
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Old 11-12-2007, 04:15 PM
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Default RE: FIberglass Mold How to Tutorial

My father does marine repair (and with the drought in our area that usually includes alot of one off hull repair). He is amazing with fiberglass repairs in my book and I am sure he has the materials lying around. I just bought a fiberglass canopy and would like to be able to do some modification and make a pile of them for some experience in working with the fiberglass itself and an airbrush.

I have seen some great airbrush work and would like to get to the point where I could do some basic paint jobs and start out from there with stripes and shapes. I love airbrushed work and think it would be a great alternative to the standard stickers approach. I am pretty much so in the same boat as you when it comes down to the scale approach...I can build it and make it look decent but it won't pass. Just because it isn't scale doesn't mean it won't look like it is.
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Old 11-20-2007, 06:54 PM
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Default RE: FIberglass Mold How to Tutorial

Here is some more on this tutorial, sorry it took me longer than I thought - pre holiday hang-ups. Sanding will make short work of this foam. I like to use a sixty grit paper on a block. One quick sanding session and this thing is really starting to look like a helicopter. I will continue placing foam in the voids until everything is filled and shaped. Continue filling with foam and sanding.

At this point, I will start to fiberglass over the foam. I have decided to hold off on forming in the turbine housing and the top of the tail section. My thoughts are that I would like to have something to place clamps on so I can check the alignment of the body halves during this next phase of the plug build.

I begin the fiberglassing process by using a brush (a cheap disposable brush is best) to cover the foam with catalyzed resin. I have decided that initially I will only do the main part of the fuselage and I will do the tail later. Once the foam has been soaked with a coat of resin (see picture below) I can start applying chopped mat over the foam.

I work the mat onto the surface of the fuselage. It must lay as flat as you can get it. I have spent a bit of time forming this fuselage. I don’t want to get sloppy at this point. Laying fiberglass mat over the foam will provide a nice hard surface for the next step of this build which will be the bondo application. Once the fiberglass has been laid, the only thing to do is let it cure. Time to put the chemicals away, clean up and let the resin cure.
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Old 11-21-2007, 09:18 AM
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Default RE: FIberglass Mold How to Tutorial

Nice update. I love the picture where you are actually painting on the resin. Noticed the degrees/diplomas framed in the background. Almost looks as if that may be a kitchen table of sorts. I was thinking that I would be toast if "she" came home and the kitchen reeked of curing fiberglass.

Smells good if you ask me

Really shaping up though, how are you getting the contour on the foam? Just eyeballing it for how it should look?
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Old 11-21-2007, 11:22 AM
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Default RE: FIberglass Mold How to Tutorial

I am with you there my friend! The pictures were actually taken in the back room of my office. It used to be my exam room, now it is my mini workshop. When my patient load slows, I simply go in the back and work on a project. I LIKE IT!
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Old 11-21-2007, 11:27 AM
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Default RE: FIberglass Mold How to Tutorial

Sorry about that, I approved the last post before answering the question. The foam is shaped mostly by sanding it level with the wooden guides. There is also some "eyeballing". Remember, I am trying to get the shape close at this point, it doesn't have to be perfect. That being said, the better I do now, the less bondo I will need later.
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Old 11-21-2007, 09:35 PM
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Default RE: FIberglass Mold How to Tutorial

did you use some sort of pattern to come up with the wooden guides?

I can see how you come up with the original plans for the fuse and what not but I guess it is just a lot more artistry than you realize. I guess if you could take a cross section of the fuselage you could get a trace of sorts and blow it up/down as needed to get an idea on those guides and then shape it. Just trying to figure it out because I can tell already that when you are done it should be impressive whereas if I were to give this a go I have a feeling it would be one crooked heli :P

I wish work was that way for me, even though it can get slow I think I might get frowned on if I broke out the modeling tools! You must be the boss
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Old 11-22-2007, 08:17 AM
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Default RE: FIberglass Mold How to Tutorial

Doc Jones,
I have not worked with fiberglass before os please forgive this stupid question, what is chopped mat?
Thanks
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Old 11-23-2007, 01:09 AM
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Default RE: FIberglass Mold How to Tutorial

There are two basic types of fiberglass material. One is cloth. Cloth is woven and has a very defined pattern. The other is chopped mat. Chopped mat has fibers that lay in every direction. It is very disorganized - almost looks like hay that has been pressed together and glued. I hope that helps. Home Depot usually sells the stuff in 9 square foot packages.
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Old 11-24-2007, 11:49 PM
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Default RE: FIberglass Mold How to Tutorial

i have a tmaxx 2.5 and wanted to kno if i can make a mold out of a lexan body or a model car body using a foam block. when u have time can u pm me and explain the process is should take. i kno that people use styrafoam to make molds for real car parts and was wondering if i could do the same here. like u said in another forum i think i want to put joy in my truck by building something on it my self. i also have an advantage on painting it because im in highschool and i take a half day tech school and do auto body and they have a spray booth there so i have the tools for that part. im planning on buying alot so i can whip up about 10 bodys( 5 for bashing, 4 for my friends, and one for show.) get back to me asap because i really want to do this so pm me when u have time. thanks so much
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Old 11-27-2007, 04:47 AM
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Default RE: FIberglass Mold How to Tutorial

u have used this green foam in ur 3d model. I have seen the same stuff in decorating flowers , where the flower stems r poked inside this foam which has been soaked in water earlier. I don,t know the technical name for this foam, can u tell me what it is called. I know it is not thermocole because it would degarde after applying resin.

I thought u would be using polymer clay to design. Have u used polymer clay in any of ur projects?

thnx for ur tutorial! looking forward for more

regards,
Pradeep
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Old 11-28-2007, 12:27 PM
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DocJones199
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Default RE: FIberglass Mold How to Tutorial

Here is another installment in this project.

After the resin cures, the surface can be rough sanded to knock down any loose fibers.
Once the surface of the plug has been cleaned up with coarse sandpaper, I can examine the pieces and decide where to go with this plug from this point. I began this plug imagining depressions with well defined edges where the windows should be. At this point, it seems that following this course will make this plug much more difficult to complete. This being the case, I have decided that the next phase of this plug build will see the side windows smoothed flush. Flush windows will make building the mold and pulling parts from the mold much easier.

After the rough sanding is complete, I can apply bondo to smooth out the surface of the helicopter. I only mix enough bondo that I can use in a few minutes. By mixing a little less bondo than I can comfortably work with, I am able to be much more efficient from a number of perspectives. First of all, I have time to work the bondo on the surface since I am not rushed by the thought of unused bondo curing on my mixing surface. Secondly, when I mix too much bondo, I end up just piling it on only to have to remove most of it later on because of sloppy application.
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Old 11-30-2007, 11:35 PM
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Default RE: FIberglass Mold How to Tutorial

OK THANKS ILL LET U KNOW HOW IT IS WEN I GET TO IT
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Old 12-11-2007, 09:24 PM
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DocJones199
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Default RE: FIberglass Mold How to Tutorial

At this stage of the build, the project gets a little tedious. Sand, prime and fill – sand, prime and fill. This process is repeated over and over until the surface is smooth and the two halves join in the center.

Spending time at this stage pays off in the end. Remember that every flaw that you are too lazy to work out of the plug at this point will have to be worked out on every piece you ever make with the final mold. In other words, you can fix a flaw once here, or you can fix it on every piece you ever make, maybe 100 times. Do yourself a favor – Fix It Now!

It is at this time of a plug build that I like to apply a nice thick coat of heavy fill automotive primer from my air gun. This primer will fill all of the remaining imperfections and it can be fine sanded, polished and prepared for the actual molding of the plug.

At this point, I believe that I am done with the helicopter plug. Now is the last time to stare at it and make sure it is right before molding. As you can see in the picture, the two halves of the plug are clamped together so that I can check the alignment. I have already painstakingly aligned the two halves but now I am reaching the point of no return. I spend a good bit of time looking at the alignment of the two halves and at the plug itself.

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Old 01-09-2008, 11:33 AM
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DocJones199
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Default RE: FIberglass Mold How to Tutorial

Sorry I have been absent from this tutorial. I found out that my pop has cancer - from smoking - been dealing with that.

Moving on to the tutorial...

I spend a good bit of time looking at the alignment of the two halves and at the plug itself to make sure that it meets my expectations. I notice obvious departures from my reference model and need to decide if I can live with the variations. Remember what I said about my expectations of model building at the beginning of this manual – I like my projects to look like what they are supposed to look like but I don’t expect them to be completely scale. Keeping that concept in mind, I can easily identify this as a Huey UH-1 so I am good with what I have in this plug.

Preparing the plug is the next stage of this build. I begin by mounting the two halves of the plug to a piece of inch thick MDF board. I attach the plugs by using screws from the back side of the MDF. Some people glue or epoxy their plugs to the parting plane. I prefer to use screws because I can remove the plug from the MDF after the mold is finished with out destroying it.

Once I have the plugs securely attached to the parting plane, I need to go around the base of the plugs looking for gaps between the board and the plugs. Any gaps are filled with clay. This is just a matter of forcing the clay into the gaps in order to prevent resin from getting under the plug. When the gaps are filled and all excess clay is removed, I can apply mold release wax to the plugs and the MDF parting plane. I like both McGuire’s and Part-All mold release waxes. It is important to apply at least five coats to the plugs in order to ensure adequate coverage. The plugs should be polished to a shiny smooth finish.

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Old 01-26-2008, 06:09 PM
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Default RE: FIberglass Mold How to Tutorial

Moving on with this turorial, PVA is now sprayed onto the plugs and the parting board. The PVA is an excellent barrier between the mold and the plug. I like to spray a coat, let it dry and then re-apply. Applying two coats of PVA can result in lost detail but that is not a concern for me with this project. An additional coat of PVA will ensure an easy release when I de-mold the plugs.


PVA is applied with my spray gun at about 60 psi and a distance of 8 to 12 inches. PVA is cheap and valuable at the same time.

For the molding process I need my air compressor and dump gun along with: tooling gelcoat, fiberglass resin and chopped mat, MEKP, rubber gloves, disposable brushes and a respirator or fume mask.

I begin by applying black tooling gelcoat with a dump gun at about 80 psi. I make sure to keep the gun close to my work because gelcoat makes a huge mess if it gets on something other than your project. I lay down a nice thick layer of gelcoat making sure to get good coverage around the base where the plug meets the board.
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Old 03-24-2008, 11:31 AM
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Default RE: FIberglass Mold How to Tutorial

Once the plug is covered with gelcoat, I let it cure to a tack. I did this project on a nice hot San Diego day so it cured to a tack in about 45 minutes.

At this step I used a different approach than I am used to. I came into possession of a large roll of veil that I decided to use in the corners and angles of the mold. In the past I have always used a combination of cabosil and resin. I found the veil easy to work with, especially when pushing it into corners with a chip brush. With the veil in place, I proceed to build the mold with three layers of 1 ½ ounce chopped mat.

I begin applying the chopped mat by brushing a nice thick layer of catalyzed resin over the area of the plug that I am working on. Then I place a piece of mat that has been pulled off of my roll and lay it on the plug. I like to keep the pieces fairly small on a project like this, no larger than 6 inches square. Pulling the mat apart will leave many loose fibers that will help the strength of my final product once it has cured. When applying the mat, I like to overlap my pieces by about 20% and build a nice flange around the base of the plug.

I let this mold cure on the plug for almost a week before demolding. This mold popped off its parting board with little effort. Likewise, the mold separated from the plugs with ease. The process for removing the mold from the plug is simple. I use a half dozed small plastic putty knives that I insert between the mold and the parting plane. Once I have one putty knife between the mold and the parting plane, I simply insert another putty knife at the edge of the separation that occurred as a result of the first knife. This is repeated time and time again as I work my way around the perimeter of the mold. Once you get started, this is an easy process.


And there it is, just how I like it. The plug is intact and the mold is relatively free of defects.

At this point the mold is inspected for any flaws, repaired and then prepped for its first part pulls.

Making parts with this mold is very similar to making the mold itself. I begin by applying five coats of mold release wax to the inside of the mold. Once the mold is waxed, I can apply a coat of PVA. After the PVA dries, I brush in a nice healthy layer of gelcoat. Once the gelcoat cures to a tack, I begin to lay resin and mat. Since this is a fairly large item, I do two layers of 1 ½ ounce mat to provide a little strength without the part getting too heavy.

Once this fiberglass gels, I trim the excess with a sharp utility knife and let the mold cure to its full hardness. Since I will be joining the two halves of the helicopter, I don’t pull the pieces from the mold until I am ready to join them. This is because any shrinkage / warping will wreak havoc with my attempts to line up the two halves of this copter during the joining process.

Removing the parts from this mold is done just as described previously. I slip a putty knife between the mold and the part. Using several putty knives, I work the perimeter of the mold to loosen the piece. I progressively dig the putty knives deeper and deeper until my parts pop out of the mold.

Once the parts have been removed, I can clean / flatten the edges with a sanding block, align the two halves and use masking tape to hold them together and seal the seam. To finish this project I catalyze about 4 oz of resin and pour it along the inside of the seam that divides the two halves of this copter. The resin is poured into the fuselage through the opening where the exhaust port would be. I then tilt the copter forward and backward to cover the seam with resin. Once this cures, I can remove the tape and deal with filling any defects in the seam.

With this post, this project is done. I apologize for the long delays between these last few posts. Good luck with your fiberglass projects. This project ended up consuming alot more of my time than I expected. I now have two helicopter ceiling fan models with a JetRanger on the way. Turns out it is a popular item. I have sold many on eBay and quite a few to folks who see them hanging in my office. It is always nice to make a few extra bucks with your hobby
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Old 09-04-2008, 09:49 PM
  #20
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Default RE: FIberglass Mold How to Tutorial

Okay so I'm a bit confused. I have read a few forums about floral foam and the effect polyester resin has on it. Some say polyester will eat the foam others say that it won't. Just as a quick reference, what is your guys' experience with the dry floral foam and polyester resin/bondo - autobody filler applied directly onto it.
Thanks.
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Old 09-05-2008, 06:13 AM
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Default RE: FIberglass Mold How to Tutorial

some foams are sesistant to resin, but all in all, the foam, or whatever you use for the "plug" is protected from the first layers by a film of wax (muli- layered), then, PVA...... then i'd spray up a layer of tooling gel, and fianally a lthin layer of resin/veil. then you can slowly build the mould up with resin/mat, i use vinyl-esther resin and thin uni-directional chopped strand matt, once the mould gets to be about 3/8" thick, ill build it up a little quicker.....

you have to be carefull not to go too fast as the mold will warp as the heat from the resin/catalyst reaction isnt dissapated slow enough...... (does that make sense?)

the most important thing in beginning the mold is to MAKE SURE the plug is waxed and PVA'D, or the tooling gel will, or can bond, permanantly with the plug..... then it will never release.

also, splits in the mold must be determined before the initial layup as to facilitate the pulling of parts from the finished mold, you cant pull from a negative draft.
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Old 09-05-2008, 09:31 AM
  #22
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Default RE: FIberglass Mold How to Tutorial

Hi! Thanks for your response. However I am more interested in specifically the reaction (if any) of Floral foam found at Michaels, or other craft stores, and polyester resin applied directly to the foam. I am thinking of making a general shape with the foam and laying glass over it just like DocJones did here, but I'm not sure if he used some sort of coating or if it was a different type of foam.
Thanks.
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Old 09-06-2008, 07:53 AM
  #23
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Default RE: FIberglass Mold How to Tutorial

take a piece of the foam, and try it..... see what it does.
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Old 10-02-2008, 10:08 AM
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Default RE: FIberglass Mold How to Tutorial

Where do you find the PVA and the Black Tooling gelcoat? Are these usually available from an automotive paint supplier, or a marine supply? Are there online sources for these products?
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Old 02-04-2009, 11:25 AM
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cherikeered
 
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Location: Oakmont, PA
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Default RE: FIberglass Mold How to Tutorial

Resin will eat almost all foams. The only foam that is resistant is polypropylene, or "EPP". But it is only RESISTANT, it will still become distorted sometimes. I work in the special FX industry making tons of molds, etc. Don't use floral foam, go to home depot/lowes and buy a 4x8 sheet of bluefoam or pinkfoam housing insulation, it is much more dense and holds excellent detail and is much cheaper. Fiberglass resin will eat it too but there is a cheap solution, Elmers wood glue, or any wood glue for that matter. Just brush it on or thin it and spray it on, at least a couple coats, works great. Make sure that there are no holes, even a pinhole will let some resin seep in and eat the foam. All you need is a layer to separate the resin from the foam. I have even seen a guy in a pinch use BUTTER! It worked pretty good actually.
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