Fiberglassing V Resin Slush Cast?

[exoray]

Casting epoxy doesn't use a gelcoat. They do not even sell it

Sure they do, but they call it a surface coat rather then gelcoat for some reason... Just Google up "epoxy surface coat"

All I do is brush it into the mold, wait an hour, and then lay the mat in and add more epoxy.

That would be the equivalent of gelcoating... All gelcoat is is thickened resin so it stays on vertical surfaces, that you apply before doing a layup it's nothing magical... In essence you are gelcoating...

I suppose what you mean is that gelcoat for epoxy is just....more epoxy.

Yeah, as I have stated gelcoat isn't anything that special it's mostly just thickened resin so it holds vertical surfaces better...

Nope. You can cast epoxy into a stone mold, no rubber necessary.

Same with any resin, it's common practice to fiberglass in ridged molds, you don't need rubber... You can cast any resin in any type of mold, this is nothing unique to epoxy... Just use a release agent, mileage will of course vary but as you stated it's only for very short runs...

That's why it's really good for doing 'one offs': casting epoxy passes through a 'green' stage, it is solid but not hard yet, so you can yank it out of hard molds without destroying the mold.

Casting epoxy and layup epoxy that should be used when doing fiberglass are two different things...

As for the "green" stage all resins obtain a similar phase while curing, it's nothing that unique to epoxy... Even polyester fiberglass layups are flexible for several hours... But, you face distortions and warping when removing said castings from a mold at this stage...

And nope again: the casting epoxy I have been getting takes about 8 hours to get 'green' hard...that is solid but a bit rubbery. It taked a full 24 hours to reach rock hard. I've never seen an epoxy resin that cures so fast....where do you get that?

Nope again to what?

Common casting urethane resins kicks in about 3-5 minutes, pretty well set solid in 20 minutes... But you can get slower versions that can take many hours to kick...

As for epoxy, there are usually three levels sold a slow, medium and fast... Pot life times range from about 5 minutes (for fast) to many hours (slow)

Polyester can be varied all over the place with the amount of catalyst used...

And with all resin types temperature plays a big part, work at 60° F and you can pretty much double the working time, work at 80-90° and you can cut it in half or more... Work at 30° and it will take forever...

Also you keep stating casting epoxy, casting epoxy and layup epoxy are two different things they are formulated for different purposes...

Nothing against epoxy it has it's place and it user friendly but it's nothing magical...

 

[Birdie]

I looked at that web site...if I'm reading that right, boy is that expensive!

Welcome to the UK, boys :unsure

 

[Ham Salad]

Welcome to the UK, boys :unsure

URF. Say, I might suggest a product to you: if you add it to epoxy, it makes it thicker and it tends to stay where you put it. One of the issues with a deep mold is that the resin tends to slide off the sides, and pool at the bottom...

There's a product here I use called 'thixo', it doesn't affect the resin's ability to take detail but it thickens it and makes it want to gel, so it stays where you put it. You might want some of that, if you want to make sure you have uniform wall thickness.

A lot of people who use fiberglass tend to lay it up really thin, it's less than 1/8" thick....it tends to somewhat fragile done this way, especiallly if you use polyester . Speakling for myself, my experience with props and actors is that
you can't make the thing too strong: hand the thing to someone and they WILL break it.

 

[Ham Salad]

Just curious, can JB weld or ardelite resin epoxy be use as well?

I don't know what ardelite is, but JB weld can be cast...I've used it when I wanted something small fast. However, it's very expensive (of course), so you wouldn't want to use for anything bigger than a couple inches. It also REALLY sticks, so you have to use 2 types of mold release (I use pva and vaselene).

 

[exoray]

A lot of people who use fiberglass tend to lay it up really thin, it's less than 1/8" thick....it tends to somewhat fragile done this way, especiallly if you use polyester .

It's only fragile when it's improperly done... The fiber is what gives it strength, the use of polyester or epoxy isn't the main factor in strength but yes epoxy does increase strength over polyester...

Fiberglass motorcycle helmets are only about 1/8" thick and perform quite well...

The problem is most people use too much resin and not enough fiber, there should be no pooling of the resin, use only enough resin to wet out the fiber any excess should be removed... Use of a vacuum bag or other method to squeeze even more resin out after you get as much as you can by traditional ways is the desired way to do it if possible... The excess resin and improper layup is what makes fiberglass weak...

Typical 1 1/2oz fiberglass mat results in .03 inches of thickness per layer, so for a 1/8" layup that is 4 layers of fiberglass... The problem is most people flood too much resin into the mix and never achieve the 4 layers in 1/8" like they are supposed to... This is what makes the layup weak...

 

[fettster]

you can go to halfords and get a cheap fast cast starter pack that has everything you need for fiberglassing.

for a gel coat, just mix in talc to the regular resin to thicken it up

thats how i started out fiberglassing, i now use a local company which is cheap so if you want the contact details let me know.

 

[Birdie]

There's a product here I use called 'thixo', it doesn't affect the resin's ability to take detail but it thickens it and makes it want to gel, so it stays where you put it. You might want some of that, if you want to make sure you have uniform wall thickness.

Is that the same stuff used for thickening up latex? Great stuff..

you can go to halfords and get a cheap fast cast starter pack that has everything you need for fiberglassing.

for a gel coat, just mix in talc to the regular resin to thicken it up

thats how i started out fiberglassing, i now use a local company which is cheap so if you want the contact details let me know.

Will check that out. If I decide to go the fibreglass route, I'll drop you a PM. I'm gonna try slush-casting first, see how I get on

 

[Ham Salad]

Is that the same stuff used for thickening up latex? Great stuff..

I dunno what it's chemical composition is or what's in it...maybe just ask if they have epoxy thickener? It's really light though, even more so than talc.
Tiny flakes.

If you put a bit in, it just makes the epoxy not tend to flow away...if you put a LOT in, it turns into a Gel. Useful with a deep/ complicated mold.

 

[Ham Salad]

It's only fragile when it's improperly done... The fiber is what gives it strength, the use of polyester or epoxy isn't the main factor in strength but yes epoxy does increase strength over polyester...

Fiberglass motorcycle helmets are only about 1/8" thick and perform quite well.....

And are not made by hand.

Polyester resin fiberglass helmets tend to crack or chip when dropped.
I suppose it's possible to do it just right and make one strong yet thin if you know just how to do it and have lots of experience...but on the other hand it's easy to make it strong by just making it thicker and using epoxy.

I tend to avoid things that require perfect technique in favor of techniques that are more fail safe and work every time. Practically speaking, it takes a lot of time and (expensive) experimentation to develop just the right technique as opposed to the more foolproof 'easy and works every time ' methods I tend to use. It's different if you have someone there who can actually teach you how to do these things, but most of us dont' have that available.

 

[exoray]

And are not made by hand.

Huh? Maybe not the cheap Chinese imports or low end models but yes many of the med-high quality helmets are in fact still hand laid fiberglass...

Shoei brand helmets (used professionally in huge volumes) for instance are still all hand laid fiberglass...

The higher end Bell brand helmets are also still hand laid fiberglass...

And I could go on, but the fact is most fiberglass of any quality is still hand laid, chop guns are only used to speed up mass produced items...

 

[Ham Salad]

Huh? Maybe not the cheap Chinese imports or low end models but yes many of the med-high quality helmets are in fact still hand laid fiberglass...

Shoei brand helmets (used professionally in huge volumes) for instance are still all hand laid fiberglass......

HAve you seen the factory? Because that 'huge volumes' and 'hand laid' don't seem to go together for me...

At any rate, the point is that I haven't seen that level of quality duplicated in a prop...event he ones made by studios.

 

[exoray]

HAve you seen the factory? Because that 'huge volumes' and 'hand laid' don't seem to go together for me...

Regardless of what you think goes together what I said is in fact the truth and is how they are made...

http://www.shoei-helmets.com/road/rd_process.aspx

Every outer shell is hand-made by one of SHOEI's skilled craftsmen.

And more details here...

http://hrca.honda.com/Articles/Article.aspx?xml=Articles/Segment/Segment_Article_50285.xml

is a construction process that integrates a matrix of hand-laid interwoven layers of fiberglass and organic fibers with resins.

Off to Bell...

http://www.wescoperformance.com/bell-helmet-features.html

Bell combines hand-laid lamination

 

[Ham Salad]

Will check that out. If I decide to go the fibreglass route, I'll drop you a PM. I'm gonna try slush-casting first, see how I get on

Remember I get one, right? You wouldn't forget me, now would you simon?

 

[Ham Salad]

Regardless of what you think goes together what I said is in fact the truth and is how they are made...

http://www.shoei-helmets.com/road/rd_process.aspx



And more details here...

http://hrca.honda.com/Articles/Article.aspx?xml=Articles/Segment/Segment_Article_50285.xml



Off to Bell...

http://www.wescoperformance.com/bell-helmet-features.html

I'm pretty sure that they dont' define 'hand made' ad 'they don't use tools and equipment'.

I'm pretty sure they have tools and technique not available to hobbyists.
I don't think their results are duplicatable in a home shop.

 

[exoray]

I'm pretty sure that they dont' define 'hand made' ad 'they don't use tools and equipment'.

I'm pretty sure they have tools and technique not available to hobbyists.
I don't think their results are duplicatable in a home shop.

Huh, first you say you are sure they are not hand laid, I show you that in fact they are... Now you do some 180 turn and say you meant they don't use tools? Hand laid or chop gunned yeah there are tools, I would love to see someone do it without tools...

Sorry hand laying fiberglass isn't rocket science and contrary to your beliefs, all the tools are readily available to the hobbiest, you just need to venture outside of the local hobby or art supply store... Same with the techinques, there are time proven and long established techniques that dominate the industry, just need to devote yourself to learning them...

Vacuum pumps, vacuum bags, peel ply, breather cloth, bubble rollers and all the other tools used to obtain professional quality fiberglass layups are very easy to obtain... I have all of the above tools and I'm just a hobbiest, never done fiberglassing as a job... Ebay is littered with the above...

Go onto some boat, surfboard, plane, race car forums and do some research, hand laid fiberglass is what they all recommend it's the desired and preferred way to do it, as the results are stronger and better then machines can do...

The problem is most hobbiest are hacks, using the wrong materials, doing the wrong procedure, and basically just doing a sloppy job... This is the main reason why most hobbiest fiberglass is not as strong or nice as it can be...

It appears you have never actually had much experience with proper fiberglass procedures and results and it's blinding you to what can be accomplished by someone who has the proper knowledge...

 

[Ham Salad]

It appears you have never actually had much experience with proper fiberglass procedures and results and it's blinding you to what can be accomplished by someone who has the proper knowledge...

Using a chop gun isn't 'hand laid' . I never did a 108 degree turn, that's always been my contention that pro chops have access to expertise and equipment not readily available to the hobbyist, and that their results are unlikely to be duplicated without same. what you 'showed' me was some very vague statements that don't in fact state that any of those companies actually do their helmets 'by hand'. They use specialised equipment.

They also use very expensive tools. Again, most hobbiest don't have access to the process. I'm really surprised that most supply places don't provide more instructions or demonstrations. You'd think they would want to encourage people to use their products, wouldn't you? It is NOT easy to figure out by yourself. Personally I had a heck of a time figuring out what I use by experimentation.

I own a lathe and mill, and I wouln't expect any home hobbyist to be able to duplicate the results I get with same...even if they had the huge amount of money to obtain such equipment. It's not home shop gear, it's pro industrial equipment (like a chop gun or a vacuum pump). They also need instructiona and experience, and sources for machinable stock. Without all this, you can't use the process. That doesn't make them a hack, it just means I have a 'leg up'.

At any rate, there are ways to do things that are better suited to the home shop, and it just makes sense to use them if you haven't got the necessary 'hands on' instruction and experience.The methods I use are indeed suited to the sloppy, but they indeed DO work...every time. If you do as I suggest, then you will come out with a strong, nice looking piece at an inexpensive price (and I'm pretty cheap). Good results justify themselves.

Since you seem know about this, how about 'sharing the wealth' so to speak, and doing some tutorials and q/a on fiberglassing? I think that there are a lot of people around here that would profit from some instruction and some good sources for materials. I've been buying at D&S, the supplier for ILM...I've got a sneaking feeling I've been paying too much.

 

[exoray]

Using a chop gun isn't 'hand laid'

Yeah, no doubt thus the reason there was an "or" between the two in my above post...

I never did a 108 degree turn, that's always been my contention that pro chops have access to expertise and equipment not readily available to the hobbyist, and that their results are unlikely to be duplicated without same. what you 'showed' me was some very vague statements that don't in fact state that any of those companies actually do their helmets 'by hand'. They use specialised equipment.

No they use the proper equipment... Just like someone making hand made furniture, they are not cutting the wood with their teeth and fingernails...

There are two recognized ways to do fiberglass, one is hand laying the other is with a chop gun...

They also use very expensive tools.

Huh? What tools are expensive? Yeah an on the fly, self mixing chop gun system is costly, but that is for the most part only used in high volume production... The rest of the tools needed to do fiberglass are no more expensive then common tools to do any job... The most expensive tool I use in fiberglassing is my air compressor ($100 model) to spray the gelcoat, my gelcoat gun is a whopping $15 harbor freight special that I drilled the tip out of... My vacuum pumps are old automotive AC evactuation pumps, they cost a whole $10 and $20 respectively at gargage sales... The other supplies like peel ply, plastic to bag rollers and brushes with are not costly either, it simply just the cost of doing it right... And in many cases I don't use them as they are not accomidating to the design...

I'm really surprised that most supply places don't provide more instructions or demonstrations. You'd think they would want to encourage people to use their products, wouldn't you? It is NOT easy to figure out by yourself.

http://www.google.com there is TONS and TONS of information out there all you have to do is look...

Go here and click on the "Learning Center" link

http://www.fibreglast.com

There is a pletora of information out there...

I own a lathe and mill, and I wouln't expect any home hobbyist to be able to duplicate the results I get with same...even if they had the huge amount of money to obtain such equipment. It's not home shop gear, it's pro industrial equipment (like a chop gun or a vacuum pump).

Chop guns are only a couple hundred dollars new comparing them to industrial mills and lathes is just silly, and as I said vacuum pumps can be had for cheap...

Also chopper guns are not the prefered way to lay fiberglass, it's simply a faster more production way to do it, the end results are not as good as hand laying... And for small projects it's simply a waste, as without a self mixer for the resin you are basically going back over and hand laying it anyway...

Since you seem know about this, how about 'sharing the wealth' so to speak, and doing some tutorials and q/a on fiberglassing? I think that there are a lot of people around here that would profit from some instruction and some good sources for materials.

Why when they are all over the internet, why waste time duplicating what is already easy to obtain? I have never been formaly schooled in fiberglassing, I simply sat down and watched videos and read tutorials and then refined my skills with hands on...

 

[Ham Salad]

Why when they are all over the internet, why waste time duplicating what is already easy to obtain? I have never been formaly schooled in fiberglassing, I simply sat down and watched videos and read tutorials and then refined my skills with hands on...

I think we'd all rather get the straight stuff from somebody who has done it and can give advice when a question arises. Saying 'it's on the internet' isn't helping. It's the same as 'just read a book': possible, but not all that helpful when learning a craft that requires hands on experience.

I'm sure you had to do a lot of experimentation before you got to where it worked well for you...why make others go through the same expenence and difficulty? Why reinvent the wheel if you can just tell others how to make one? When birdie asked for advice I didn't tell him ' Go read a book', I gave him practical advice he can use (I hope).

ANY tool that costs more than $20 is an expensive tool...and if they require modding into a tool then that isnt' practical either (you have to know how to do it and why). What helps is actual sources where you can buy the thing and advice on how to use it, specifically.

Again, I think you would help a lot of people if you shared your knowledge in a practical way...

 

[Birdie]

Remember I get one, right? You wouldn't forget me, now would you simon?

Nah! :lol

So, I picked up a cheap glassing kit (polyester) today and laid up a couple of test pieces from 300g mat.

Worked out okay, but very thin. How many layers would it take to produce something like the 300 helmet in the video that was posted in the video earlier in the thread?

 

[cheech9898]

# of layers required is really determined by strength requirements & by the resin system used. As it was mentioned before layup technique will effect strength if there's excess resin... In general if you have good wet-out & layup technique with out any over use/pooling of resin and no air bubbles you can most likely get away with around 4 layers. If you know the type of use the project will have, adding a few extra layers to abuse/stress points may be a good idea.

Only other thing I can think to add to the comments about using a thickening agent to the resin for gelcoats/surface coats is make sure to read the MSDS on the agent. Many Epoxy thixotropic agents are a fumed or colloidal silica (like Cabosil & West System's 406)... nasty stuff to accidently breath in and they can be a very fine/ eaisly airborne powders. Talc & if you can find it a very fine methylcellulose powder (not a course powder like Metamucil) would be better/safer and to some extent if you want a metal finish aluminum powder well thicken it up for you too.

If you want a decent introductory book, check your local Borders or Barnes & Noble for:
Fiberglass & Other Composite Materials: A Guide to High Performance Non-metallic Materials for Race cars. Street Rods, Body Shops, Boats and Aircraft
It's usually in the automotive repair section and covers the basics pretty well.