Fiberglass Resin and Cheesecloth

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RevMarx

New Member
I am in the midst of making a couple of props for an upcoming steampunk larp game at Origins. Among them is a deep sea diving helmet. I have never made something like this before, but I have read a few blog from others who have. I am mostly making it up as I go along, and could use any advice that is offered.

To start with, I covered an inflatable beach ball with petroleum jelly (so it can be removed later), and then covered it with paper-mâché (not very thick, because I hate working in paper-mâché). That was not going to be strong enough, so I decided that I should try covering it with fiberglass.

I have only ever used fiberglass once before, and it was a mess. Anyway, to save on bulk and cost, I thought that I could maybe substitute the fiber mat with cheesecloth, since I don't really need it to be super strong, and I thought the cheese cloth would give the resin strength just like the glass mat would, for super cheap. I did a little digging on the web and did find some evidence of cheese cloth being used with fiberglass resin by a couple of artists, but no details of the process.

My main question is this; has anyone ever used cheese cloth with fiberglass resin? If so, how did it turn out? Does anyone have any pointers on this technique? Just to be clear, I am talking about what Americans call cheese cloth (like gauze) , not what people form the UK call cheese cloth which, as I hear, is something else.

I've worked on two pieces so far, and it has not been as easy to work with as I imagined. For my next test piece, I am using spray glue to adhere the cheese cloth to the object first, then adding the resin. Adhering the cheese cloth with the glue went much smoother than it did applying it directly to the base coat of wet resin, but I have yet to see what happens when the resin is brushed on (tomorrow's goal).

If anyone has used this technique, or has any general fiberglass tips, or really and advice at all for this project, I would love to hear it.

-Rev. Marx
 

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dmaul

Active Member
RPF PREMIUM MEMBER
Could you describe your first time "mess" with fiberglass? Just want to know more details as to why it was not a success for you. The only advice I can think of is to cut your fiberglass into smaller managable pieces or strips. Lay the first strip down after you brush on some resin on your helmet. Then brush resin on top of the strip to get it to contour to the helmet. Overlap the next resin strip and continue. Know your working time and only mix enough resin before it hardens in the mixing cup. It all depends on your pot life and working conditions (temp, humidity, etc...). Good luck with the cheese cloth method and let us know if it works. Thanks!
 
I dont think i would use cheese cloth, all your strength comes from the mat, not the resin. With the cloth so loosely put together your probably going to have a resin rich part, which one will be brittle and two will probably shrink on you. Especially if your using polyester resin.

Just something to think about.

Al
 

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robn1

Master Member
A lot of car stereo shops use cotton fleece to make subwoofer and speaker enclosures. That should work better than cheesecloth, and be less messy than fiberglass. But fiberglass woven cloth isn't that bad to work with really, chopped mat can be a mess though.
 

mdb

Sr Member
You're right IEDBOUNTYHNTER. Anything other than proper mattng/cloth is going to be brittle and shatter- and pretty easily. I have experienced this myself ;) That said you can start with a base of say stretch fabric, resin that and then get matting over/under that. It's how (some) custom car interiors are made. The stretch fabric conforms to the shape and gives something for the resin to adhere to and you can then build up from there. Done this myself and it works very nicely as a base to work over.

On going M3 project *Pics inside*
how to fiberglass engine cover pics
DIY Trunk Corner Subwoofer box - Toyota Nation Forum : Toyota Car and Truck Forums
Teaching Fiberglass (part one and two) - S-10 Forum

lol! I was typing as the last reply came through but now you have some examples to work with :)
 

3d-builder

Sr Member
Here is the matting i used to just strengthen up the under side
of my speeder, i used the Z-poxy it worked well, very little
odor as well. The matting is much stronger than cheese cloth
will be, if you look close you can almost see the weave.



Thanks for the help on that Al!:thumbsup
 

RevMarx

New Member
My first attempt at fiberglass (in the past) was a mess, but not a failure. I successfully managed the repair I was making, but it wasn't pretty by any stretch of the imagination. The cut fiber mat I was using was very difficult to work with. It kept wanting to cling to the brush and generally not go where I wanted it to go. The resin was very sticky and messy, and also difficult for me to work with. The finished product was all spiky and uneven and looked nothing like the examples I have seen of other people's work with fiberglass, but it did work. Of course it was my first time, so maybe just being unfamiliar with the product could account for the poor performance.

I think that must have been a different brand of resin, as it was a translucent green and dried very hard and ridged. The one I am using now (bondo brand) is a dark amber in color and is still a little flexible (very little, but still) when dry.

I probably should have used the fiber mat (woven glass cloth would be too expensive for me), but I thought it would add too much thickness. I was hoping that just a thin layer would give the sphere enough rigidity to be functional. Again, it is just a costume prop for a larp (which will probably only run once) so it doesn't have to be terribly strong.

Ok, so here are the results of my first tests.
On a plastic 2-liter bottle (air tank for the costume) -
All I really wanted to do was make the bottle more rigid. I started with a coat of resin on the bottles surface, and then tried to wrap it in strips of cheese cloth (about three inches wide) in a spiraling pattern. That didn't quite work out as easily as I had hoped. It was difficult to bet to behave (like I remembered the glass to be back in the day) and I only got one strip on with very spotty coverage. After it was dry, I tried again with a second layer. This time I used spray glue to adhere the cheese cloth to the bottle first. That seemed to work out well. It was much easier to position and get to go where I wanted it. Then I coated the thing in resin. The resin did tend to loosen the glue and make the cloth move on me after it was saturated, but by then I was just about done brushing anyway, so the finished result was much nicer. When that dried, the bottle was nicely rigid, with only a couple of softer spots that didn't get even coverage apparently, but it has a very uneven surface (yes, I expected I would have this and need to do a lot of sanding and filling). In the end, the fiberglass coating did achieve the rigidity I wanted, with a fairly thin coating, and very cheap, but I think it was the wrong direction to go for this part of the project, and I have since started over with another method not involving fiberglass.

On the sphere -
I started out with a paper-mâché sphere and I brushed on a single coat of resin with no cloth and let it dry. That went Ok, and it took about two ounces of resin to complete the coat. It added a small amount of rigidity, but basically made the paper-mâché kind of "leathery". Then I used the spray glue technique I had tried on the bottle and glued a layer of cheese cloth to the surface of the sphere. It was mostly a single layer, but maybe a third of the sphere had a double layer from overlap. That went fine. Then I brushed on a coating of resin, which went about the same as it had on the bottle. The cloth started to move around on me and get unruly when it got saturated, but it was manageable. This time it took about ten ounces to cover the sphere. When dry, the surface was much more rigid, but still a little flexible, especially in the single layer areas. It is definitely not brittle (as far as I can tell), and I'm even going slightly "hot" (using one drop more of activator per ounce than the instructions say, be cause it is only about 50-60 degrees in my shop). Of course the beach ball is still inside for support, so that may change once I take that out. It is not quite as rigid as I want, so I may need to do another layer.

So far for an unproven technique and a material I'm not familiar with, I think it is working out about as well as I could hope. I do agree that it would probably have been stronger and needed only one layer if I had used the glass mat. Probably should have. I think that there may be some rare applications where the cheesecloth would be a good material, but I doubt most of you would want to use it for most of your projects.

I was hoping for a very fast, easy and cheap way to make the paper-mâché ball rigid. That's not really what I got. for the amount of resin and work that is going into this, I probably should have spent more on a better sphere to begin with and skipped the fiberglass idea. Anyway, thanks for the replies. I'll keep posting my results. I took a couple of pics. I'll post them as soon as I get them out of my camera.

-Rev. Marx
 

hansicle

Sr Member
When I have done fiberglassing in the past, I did it the cheap and easy way. Most of the supplies could be found in the automotive, or adheasive section of larger hardware stores. The fiberglass cloth wasn't that expensive. You can make a pretty rigid shell out of the fiberglass, and bulk it up and smooth it out with a layer of BONDO.
 

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exoray

Master Member
Well my first piece of advice is practice, the more you do fiberglass the easier it gets... Yes, the first time was horrid but the more I do it the easier it becomes and it's now pretty painless...

Watch all the videos and tutorials on Youtube you can find, watch what they do and tyr to copy the techniques they use...

Now as for alternatives, you can use the paper-mache technique but instead of some flour based paste use a watered down quick set plaster... I use Sheetrock Easy Sand, you can get it in 5, 20, 45, or 90 minute set times... Most paint stores will carry all the set times, and Home Depot type stores will generally only carry the more popular 20 and 45... I would suggest the 20 as a starting point, if you mix it with different temp waters you can move the kick time up and down, start with room temp water and a CLEAN container (if you use a contaminated from a previous mix container it will really cut the work time) Anyway you can mix this stuff way down to a syrup like consistency and it will still setup just fine... It will make a much harder shell than traditional paper mache, but it's still plaster so it will break if impacted... You can brush on more of the plaster and sand smooth... Seal with Shellac, and paint...

That is a poor mains layup, should cost you about $10... Nowhere near as strong as fiberglass but cheap and fast...

Another method to add strength and this works well if you are building a 'mascot' type bobble head is to get a bunch of t-shirt scraps (painters rags) and soak them in a 50/50 blend of water and Elmers glue and layer them over the paper mache and let dry (it will take a week or so to fully set) You won't have a smooth surface but you will be amazed at how resistant the cloth Elmers glue is once it's set...
 

Pilot

Sr Member
RPF PREMIUM MEMBER
Cheap paper towels make an astoundingly good substitute for glass cloth. I wouldn't have believed it if I hadn't tried it myself.
 

RevMarx

New Member
OK, so, here's the resin I'm using. It doesn't say if it is "waxed" or "unwaxed", so I have no idea. Once it is dry, it is not tacky, so I guess it is waxed.


Here is my first pass on the bottle, the one which was difficult and only got very spotty coverage (one strip of cheesecloth). The end has been rounded out with some rigid foam and sanded to shape.


Here is the same bottle, after a second coat of resin and cloth, and after a very quick sanding. It actually came out better than I had thought, but would still require a lot of bondo and sanding to make smooth.


Here is the sphere (I use the term loosely) after the ball has been removed.
It is still very thin, light , and fairly rigid. The removal of the ball did not seem to take away any of the rigidity it had, so that was all fiberglass. It does still have a little bit of give to it, and clearly it is not terribly strong. I'm not sure yet if I will give it a second coat. I probably will, after I cut the portholes and add some of the other features. It holds its own shape just fine, but clearly won't hold any significant weight or put up with much abuse, which is basically what I was looking for.


I'll probably also give it a coat of resin only on the interior of the sphere, to seal the paper-mâché.

So far, my assessment is that this technique does have some merit, but its application is limited. I don't see it being used by very many people very often. It certainly does seem to work, and the biggest drawback that most people mentioned is that it would be brittle, which it does not seem to be. And that it would be weak, which it is, but its also very thin, and only really has one coat to it.

I really like the paper-mâché with plaster idea. I may try that sometime.

-Rev. Marx
 

3d-builder

Sr Member
I know your trying to save on cost.... here is the fiberglas cloth from hobbico they have medium and heavy cost about $5, the Z-poxxy was less than $15 i think so for $20 or so your set.....and real strong.:thumbsup
 

feek61

Sr Member
I just bought a yard of 2oz glass cloth for $5.99. I don't think I would skimp on the structural part if I were you.
 

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Themovieman

New Member
One of the main problems with the cheescloth idea is your matte/cloth (in this case cheesecloth) to resin ratio. I think it was already mentioned that the strength dies not come actually from the resin. It is more or less a bonder or adhesive for the matte or cloth. Different mattes and cloth are a pretty big subject, but you really should be using a chop strand matte. This is easily found at the Same location you found your resin. Cloth (people argue with me on this) is really not designed or intended to be used with polyester resin by itself. It may be used in conjunction with chop strand matte to achieve different physical propertys depending on your needs. Epoxy however, is compatible with cloth. Also it is important to note that the cloth should be layed up in matte while its wet, not after its cured.
Using polyester resin and matte is actually a pretty simple process. Chop strand matte is made of loose pieces of chop strand(obviously) that is held together with a binder, or glue that holds it in its sheet form. The styrene in the resin (the part you smell) dissolves this binder leaving thousands of strands of chopped matte floating in the resin, thus slowing you to form it to your shape. Properly catalyzed resin is also very important. If the resin does not gel in 12 - 25 minutes, its not catalyzed properly.

Don't forget protective gloves! Hope this helps.
 

exoray

Master Member
If the resin does not gel in 12 - 25 minutes, its not catalyzed properly.
This is not true, there are valid reasons to slow the process, and it doesn't make it improper... In fact many epoxy based systems are designed for cure times well in excess of 30 minutes, and it generally yields a stronger piece... There is no way you can properly vacuum infuse or vacuum bag an entire 40 foot boat hull in 12-25 minutes, this is a prefect example of when a slower cure system is implemented...

The biggest 'improper' thing that most newbies do is over catalyze the resin and thus burn it, this is evident with an amber or brown shift in the resin mostly evident in polyesters...

Cloth (people argue with me on this) is really not designed or intended to be used with polyester resin by itself.
Sure it is depending on the application, properly done woven cloth is 'stronger' than random chopped strand regardless of the binding agent being epoxy or polyester... That is why high tech laminates like carbon fiber and kevlar use a woven cloth pattern... A woven cloth sub-straight done properly always offers a superior weight to strength ratio, but at $ cost...
 

RevMarx

New Member
Especially if it were a few layers thick, I don't really see why cheese cloth wouldn't be as strong as glass mat or cloth. (OK, maybe not AS strong, but sufficiently strong for most hobby applications) It is a fiber, so it gives the resin something to cling to. It is woven, so it has good tear strength, and the strands have a pretty decent tensile strength. I have used it to strain and squeeze berries for the juice, and I can say that it will put up with quite a bit of pressure. Just two layers thick and I couldn't squeeze it hard enough for it to burst. Sure, one or two layers of cheese cloth will rip before woven glass cloth will, but look at how many fewer fibers per inch it has than glass cloth.

So far I'm not really that displeased with the cheese cloth. It's actually working about as well as I had envisioned. Again, this is a project that doesn't really need a lot of strength, just the ability to cheaply hold its shape under casual use and handling. My biggest surprise is that it has as much flexibility as it does. I expected it to be more rigid and brittle.

Someday when I don't have a project deadline to deal with, and when I have a few bucks to waste on materials, I'd like to do an objective comparison test.

-Rev. Marx
 

exoray

Master Member
I don't really see why cheese cloth wouldn't be as strong as glass mat or cloth. (OK, maybe not AS strong, but sufficiently strong for most hobby applications) It is a fiber, so it gives the resin something to cling to.
You are focusing on the resin, the resin doesn't need something to clinging to, the fiber needs something to hold it in place ;) The strength is in the fiber not the resin...

but look at how many fewer fibers per inch it has than glass cloth.
Strands per inch is what you want, you don't want the resin bridging gaps with no fiber support, that weakens the structure...

Using cotton fiber vs nothing at all is certainly better, but it's far inferior to fiberglass in the end... And $ for $ it's hardly a huge cost savings in the end... It's common for people to use cotton flock as a thickener for resin as it does add some strength but it's nothing to brag about... You can use any type of fiber to strengthen a resin, laminated counter tops are simply resin and paper, and it's common to see cotton impregnated in rubbers for strength, lots of rain coats are like this... But I don't know of any common practice of using cotton fibers instead of fiberglass beyond decoration...

Is it good enough for hobby related stuff, maybe I just don't really see an advantage in the end...
 

Themovieman

New Member
Your right exo, there are reasons to slow. There are also epoxys, vinylmodified, vinylesters and polyesters designed for faster Or slower cures. I was specificly speaking of the general resin the average hobbiest might pick up at they're local hardware store. These resins were designed to gel (for maximum phisical propertys) in 12 - 25 minutes. Sure you can under or over catalyze these products and achieve something that works for your needs. I realize we're not making airplane parts, so I appologize for being critical on specifics.if it works for your needs, then your doing it right.

When it comes to cloth/matte,.. epoxys, vinylmodified, and vinylesters are a completely different animal than the polyester resin someone buys at a hardware store. I would never use a general polyester with out matte included, but again I speak in a structural means.

Revmarx, glad its working for you. Good luck on your project!
 

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