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 Post subject: Types of Fiberglass - A Primer
PostPosted: Tue Oct 30, 2007 9:35 pm 
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Here are some notes I've taken on a fact-finding mission to TAP Plastics. When I explained that I was gathering information for fellow Star Wars fans, the manager was kind enough to cut me various samples and explain to me in layman's terms what the pros and cons of each type of fiberglass they carried.

For those of us who are newcomers, it's easy to hear how strong a certain fiberglass (FG) is and not realize that there are other parameters to evaluate FG against. In our application which is primarily prop helmets and armor, we don't necessarily use the same kind of FG that are used in boats. Boats may call for cost effective weaves that are very strong and just moderately flexible to handle stress against their hulls. However, in our hobby, the thinner and more supple the fiberglass is, the better it will lay up against the subtle details of a mold.

Basically, we need fiberglass that is supple, that handles corners and contours well. The more supple the material, the better it will form to the details of a mold (think silk versus a floor carpet). Those qualities are found in fiberglass mat rather than cloth. Fiberglass cloth is a dense weave where the woven structure will make it less supple and it may not contour or corner well when laid up within a mold. In the case of one of my very first fiberglass and resin kits, the FG used was cloth (possibly S-series), which left many areas plain resin because the thicker cloth wasn't flexible and supple enough to form the essential details of Vader's face. Some of the better Vader FG kits I've seen use a short, thin strand of FG mat instead of woven cloth.

Those of you who are more experienced, please feel free to chime in. This post serves merely as a starting point to give a basic exposure. It is by no means intended to be authoratative or comprehensive. Also, do realize that these strips you see are just small samples. You can basically purchase them in large sheets by the yard (except for Tape which is whatever widths they come in).


Mat Glass

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Featured above is 0.75 oz mat glass. The TAP Plastics Manager knew I was talking about Vader helmets as the appication and related that this type is good for compound curves and tight corners.

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This one, above, caught my eye. This is an ultra-thin surfacing veil mat. As many of you have experienced, the standard mat glass functions well unless one single strand of glass lifts and pokes you in the face like a needle. This veil mat reminds me a lot of the FedEx white colored packaging (you can see reinforcing fibers with in the paper). It appears to have a lot of potential as the final layer(s) of FG to create a subtler texture.


E-Glass

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The "E" in E-Glass stands for "Economical". E-Glass comes in lightweight, midweight and heavyweight cloth weaves suitable for boat hulls. In our hobby, from just personal experience, cloth as a weave is a bad choice for helmets where you need a lot of flexibility and cornering for all those facets and corners of, say, Vader's facial features.

I can imagine someone might try using this kind FG for Vader's chest armor and possibly shin armor where you are covering large surface areas with no significant structural detail. For Vader masks and the like, this is not the way to go. There are some "studs" on the shin guards and subtleties on Vader's chest and shoulder armor. Mat is preferable for costume armor, but if unavailable, S-Glass might usable for armor.


S-2 Glass

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The "S" grade seems to be good for surf/sailboards. It's 30% stronger than E-Glass and 15% stiffer. This might be a better choice for armor if a good strength-to-weight ratio is needed. My experience with this in a vendor's helmet kit was abysmal. The cloth of that kit was in patches and caused the interior to look very cheap. For some reasons that vendor's FG didn't form seamless layers with the resin in that it created massive air pockets which means there was structurally no protection for large areas and so the FG in that vendor's helmet was utterly useless. This is not to say S-2 Glass is useless for our hobby if used properly. Helmets may do better with mat, as I have been told by experienced prop-builders.


Fiberglass Tape

This one is interesting because this comes as a roll of "tape" (no adhesive). Featured here is Knytex tape which is basically fiberglass mat and fabric woven together. It's very strong and good for repairs, but it's stiff, doesn't stretch, and is not supple at all.

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Above is Knytex Tape. This is basically two different kinds of fiberglass: mat and fabric. This is good for applications where you need a good deal of strength. It's possibly stronger than E-Glass, but because it's not supple at all and is a poor choice for Vader helmets.


Last edited by CSMacLaren on Tue Dec 04, 2007 10:58 pm, edited 1 time in total.

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 Post subject:
PostPosted: Thu Nov 22, 2007 6:31 pm 
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That will prove very helpful to folks Mac, good idea.

Now its time for a primer in the types of resins. ....polyester...epoxy.... :)


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 Post subject:
PostPosted: Thu Nov 22, 2007 7:36 pm 
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this is awesome info Mac!! :as2 is there any chance the Mods can make this into a sticky?


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 Post subject:
PostPosted: Tue Mar 25, 2008 5:22 pm 
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A few more things to remember with fiberglass matting are that there are different weights, which are usually measured in ounces beginning from 1/2 oz up to 6 oz or more. The higher the weight the stiffer the material. Remember though, higher weight does not mean more strength. Surface veil isn’t measured in weight because it is designed for a specific purpose, that being as a finishing layer. Surface veil is never be used as a material to give strength.

A coupe things to keep in mind when working with lower weight matting is that lower weight fabrics are easier to work with for detail, but you need to build more layers in order to build strength. You also run the risk of pulling the material as you work it into the gel coat. This can cause surface ripples on the casting that you will only see after you have demolded.

Resins:

There are different qualities and types of resin. Do not fall under the trap of thinking that all resins are the same, or will do the same job.

Some resins are waxed while others are unwaxed. Each have different attributes. In some instances, you might prefer a waxed resin, while in other circumstances an unwaxed may be a better choice.

Besides waxed and unwaxed there are different types of resin. For exampl; the standard resin is Polyester, but there are a few different types of polyester resin. There is the standard resin that you can find everywhere. (It comes as waxed or unwaxed.) Then there is Isophthalic resin and Crystic resin.

The Isophthalic resins are designed to have a different molecular makeup whereby as it cures the molecules bond to themselves more completely. Think of it like Velcro. The Isophthalic Resin has more barbs to hold on better and give more strength, a better bond and a more complete cure.

Crystic reins are used to bond different types of materials together. ABS plastic to Nylon as an example. Part of the way it does this is by shrinking around the material that it’s applied to.

These are only a few of the resin choices available, and the most pertinent to our hobby. As you can see, there are a number of factors to consider when choosing the materials for a project. There are still more decisions to be made on the type of Gelcoat to use. Some may not be appropriate for your application and can lead to disastrous results.

The world of plastics is fascinating. You can spend a lifetime learning the subject. I hope this addition was helpful.

:cheers
JB


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PostPosted: Tue Mar 25, 2008 6:12 pm 
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verry helpfull JB!! thanks!! what would you suudgest a good resin to use for a Vader mask?


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 Post subject:
PostPosted: Tue Mar 25, 2008 7:22 pm 
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VEGAS VADER wrote:
verry helpfull JB!! thanks!! what would you suudgest a good resin to use for a Vader mask?


If you don't want to get into making your own gelcoat I would use a black tooling gelcoat with 1oz matting and an unwaxed polyester resin. Get a good quality polyester resin. You don't need Isophthalic resin. Isophthalic resins are tricky to work with, especially if you're not very experienced with fiberglass.

BTW, one point that I would like to make about fiberglass mattings is that woven roving (Or woven matting.) is very good for flexibility whereas stranded matting is good for strength, but not as good for flexibility.

:cheers
JB


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 Post subject:
PostPosted: Tue Mar 25, 2008 11:44 pm 
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:thumbsup Good thread...


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