Again gelcoats, forever and ever

[oneilmemo]

To be honest i know nothing about boats but i have been assigned to make an extensive research about gelcoats and that is why i am here. i have a few questions and need some verifications. i hope someone will help me:
- i have been assigned to represent gelcoats within an absolute and general formula that will be valid for all-purpose gelcoats. so i divide gelcoats into 3 subtopics 1. base-resin type 2. additives 3. inhibitors/catalysts. resin types are listed and limited as epoxy (especially), unsaturated polyester, vinylester, thermosetting acrylate and phenolic. i divide additives as fillers (there are lots of fillers), pigments, thixotropes, suppressants, UV inhibitors, fire retardants and conductive agents. i found only one inhibitor or catalyst or accelerator which is MKEP (if you know more please tell me). If there is nothing wrong up to here i want to ask my questions:
- Since gelcoats are derived from one of the resins above, the gelcoat will exhibit ALL the mechanical and physical properties of THAT resin whatever the additives or inhibitors added. Is that right? If so, what happens if i try to utilize from two or more combinations of resins as base resin?
- and the additives.. Do they make any chemical reaction with polymer bonds so that change their chemical properties or are they (resin+additive+inhibitors) together just a homogeneous mixture in which both resin and the additive exhibit their properties separately?
- as you know each type of resin type i listed above are also divided into subtopics say epoxy has bisphenol, novalak bla bla types or uns. polyester has orto- iso- etc. types. Can i make such a generalization: all types of say again epoxy resins can be used in forming gelcoats? Is there any restriction for resins to form gelcoat?
- one more question.. for example i have a raw composite material which has polyester resin that is reinforced by say glass fibers. Can i use any gelcoat that has any type of base-resin? Is it like blood type conflict or any gelcoat type can be applied to any composite material?
- finally (i hope so) is there any possible application of gelcoats during or after any process regarding composite materials (like filament winding or vacuum infusion etc.)
For now that's all. Thank you all already.

[the1much]

hahhhaaahahaha,,,,,,, sorry dude,,, you just made me not want to EVER gel-coat again. hehe :D

[oneilmemo]

it is an honour for me to make you laugh. i wish you could share this honour with me dude and try to make me laugh by helping?

[the1much]

ill make ya laugh by telling you ,," to me, theres a big difference in knowing all there is chemically with gel,,,, and being able to use it the right way."i can do any kind of gel work,, have done it for years ,, but NEVER have i read a label,, or want to know all the complications of each gel, what each is made from, what each chemical does,,,,,all that stuff is "book learning",, which is WAY different then "piratical learning"
MEKP,, is the only cat. that i know of.
mixing resins "together" i cant imagine would do any good,,, only bad.
and if you mix gel, additives, cat.,,, they MUST bond together,, or NONE of them would work,,, it would be like oil and water,, they would always separate.
and mixing resins work if you do it the right way,,,,,,example,, epoxy will bond to poly,,, BUT,, poly wont bond to epoxy.

im sorry dude,,, i aint got NO "book smarts",, im just a simple "pee-on" ehhe ;)

[oneilmemo]

You're rigth they are all book stuff and i hate that way too. But as i said this is an extensive research and i have to complete in one week i guess by writing a report :S. and to me, i am just a trainee with nothing but google cause there is no speciality of any book in our library on gelcoats. But i can say we are both laughing now. Thanks dude.by the way could you give more examples like epoxy gelcoat can be applied on polyester based composite but poly wont bond to epoxy as you gave above? i will be gratefull if you mention all the possible combination you can give with a little scientific reason.

[the1much]

epoxy will mechanically bond to poly,, and a little chemical bond. poly will only mechanically bond to itself after the first coat is 24 hours old,, before the 24 it will chemically bond. vinyl will mechanically bond to poly,,, and to itself(after 24) before that,, it will only mechanically bond to poly, and chem. to itself. but NETHER of these will bond to epoxy. but epoxy will bond to them the same as to the poly.
im not an
"epoxy dude" i've used it on small parts and small applications,,, ive built 1 boat with it,,,but these guys on here have taught me alot.
you should search for member " Par" ,, him and a few others know a WHOLE lot more then me on this "book smarts" hehe ;)
again dude,,,, im sorry i cant be alot of help,,,, i dont think i have EVER written a report in my life,,haha,,, and the only books i "read" are the ones with lots of pics of nekkid women,,haha :D

[tinhorn]

Well, maybe I can add to the1much's Dearth of Knowledge.

I divide gelcoats into 3 subtopics 1. base-resin type 2. additives 3. inhibitors/catalysts.

resin types are listed and limited as epoxy (especially), unsaturated polyester, vinylester, thermosetting acrylate and phenolic.

I've used polyester and vinyl ester gelcoats. Thermoset acrylate and phenolic MAY be those plastic sheets that are formed in a mold, then fiberglass applied to the sheet. They're not gelcoats, but have advantages of pretty patterns such as marble or granite. They're also for sissies who can't spray 18 mils in three passes.

Vinyl ester gelcoats are said to not give as high a polish as polyester. When I was in the business, urethane gelcoats were available which were said to provide superior "shiny".

i divide additives as fillers (there are lots of fillers), pigments, thixotropes, suppressants, UV inhibitors, fire retardants and conductive agents. i found only one inhibitor or catalyst or accelerator which is MKEP (if you know more please tell me). If there is nothing wrong up to here i want to ask my questions:

Pigment is your color, of course. Thixotropes are what give the gelcoat the ability to hang on vertical surfaces (or upside-down). With no thixotrope, it would run off like syrup. UV inhibitors help keep the gelcoat from dulling in the sun. Fire retardants keep the gelcoat (and presumable the resin) from supporting combustion.

I'm not surprised that MEKP is the only catalyst you find. That other one (whatever it's called) will cause discoloration.

- Since gelcoats are derived from one of the resins above, the gelcoat will exhibit ALL the mechanical and physical properties of THAT resin whatever the additives or inhibitors added. Is that right? If so, what happens if i try to utilize from two or more combinations of resins as base resin?

- and the additives.. Do they make any chemical reaction with polymer bonds so that change their chemical properties or are they (resin+additive+inhibitors) together just a homogeneous mixture in which both resin and the additive exhibit their properties separately?

- as you know each type of resin type i listed above are also divided into subtopics say epoxy has bisphenol, novalak bla bla types or uns. polyester has orto- iso- etc. types. Can i make such a generalization: all types of say again epoxy resins can be used in forming gelcoats? Is there any restriction for resins to form gelcoat?

- one more question.. for example i have a raw composite material which has polyester resin that is reinforced by say glass fibers. Can i use any gelcoat that has any type of base-resin? Is it like blood type conflict or any gelcoat type can be applied to any composite material?

These are good questions for your gelcoat supplier.

- finally (i hope so) is there any possible application of gelcoats during or after any process regarding composite materials (like filament winding or vacuum infusion etc.)

I've seen resin tinted with pigment for both open mold and resin transfer processes. After the part has been made, sure, you can spray it with gelcoat.

For now that's all. Thank you all already.

My pleasure.

[juiceclark]

Excellent synopsis th.

One can also take the dumbass approach like me: I asked the dude who has owned the fiberglass supply company for 40 years which gelcoat to use on my project. Bought him lunch after he took an hour to visit my project and told him the picture of his wife in his wallet is real perdy!
If my experience is any indication, not only will he suggest the perfect products for your project in great detail, but he'll sell them to you for the same price as that huge boatbuilder down the road. (he doesn't like them)

You can never know everything in this or any business. There's just too much to know. Find smart people and make them your friends...it's your only hope.

[the1much]

well Thanky T.H.,,,, and J.C. ,,, man this dude makes me feel stupid,,hahahaa :D

[tinhorn]

One can also take the dumbass approach like me: I asked the dude who has owned the fiberglass supply company for 40 years which gelcoat to use on my project.

Yup, that's my favorite. I used to have one awesome sales rep - an old dude who would get me samples of ANYthing. "Hey, tell me about this ceramic filler I read about." Poof - the guy brought me an entire bag. I asked about plastic microspheres and got a whole box. It was huge! Parabeam, graphite/kevlar weaves, whatever I was curious about trying, he'd bring me like a year's supply - free! And hell, I was operating out of my garage at the time!

I asked him about it once. He said he treated little guys just like the big guys because his biggest accounts had also started in their garages.

[the1much]

hehe,,, wanna know why i ALWAYS ask em what i should use?,,,, so when its wrong THEY get charged for the re-do hehe :D:D;)
i STILL do it with awl-grip.
i think the "smart" people in the boating industry are the ones that cover their @sses !! hehe :D

[oneilmemo]

Thanks to all of you dudes, i am shocked rigth now, what a chat! i know this will shock you messieurs and i am terribly sorry but i still doubt about these questions:
- Since gelcoats are derived from one of the resins above, the gelcoat will exhibit ALL the mechanical and physical properties of THAT resin whatever the additives or inhibitors added. Is that right? If so, what happens if i try to utilize from two or more combinations of resins as base resin?

- and the additives.. Do they make any chemical reaction with polymer bonds so that change their chemical properties or are they (resin+additive+inhibitors) together just a homogeneous mixture (mechanical bonds only) in which both resin and the additive exhibit their PROPERTiES separately?

- one more question.. for example i have a raw composite material which has polyester resin that is reinforced by say glass fibers. Can i use ANY gelcoat that has ANY type of base-resin? Is it like blood type conflict or any gelcoat type can be applied to any composite material that is to be gelcoated?

by the way i wish i could be smart but i am just a prisoner of education.

@ the1much
these couplings about bonding of resins you did yesterday.. I recognize now cause i couldnt have read carefully due to running out of time and i am sorry my reply is quite late now. Anyway these couplings are really important to me; are they for mixing the resins for forming a base-resin of a gelcoat or did you mean epoxy gelcoat will chemically bond to a polyester composite material by saying that epoxy will bond to poly?
- One more questions could you suggests a gelcoat formula for something like that:
I have carbon fibers impregnated with epoxy resin just before filament winding. i want to make a motor case which has a inner surface that will resist to heat up to 200-250 celcius degree and i want the motor case not to leak the liquid fuel and could conduct electric current. what type of gelcoat you can suggest? this was my estimation (i made up whole the example) but they will ask me something like that so i just tried my chance.
Thank you all already

[the1much]

1 -yes,,,,,,,,and you cant mix different types of resin together

2- no ,, additives does not change chem. properties

3- YES you can,, if done the way we explained before,,poly with onoy poly,,vinyl with vinyl or poly,, epoxy with all

4- epoxy resin is epoxy no matter what ( gel,, glass resin) its in. them bonds go cross the board no matter what we're talking bout.

last one--- NOPE ,, you wont find any gel to stand up to that heat,,, most "high temp" paints wont handle that heat.and NOPE you wont find any gel that holds up to fuel.an i have NO idea about conducting electric,,,, never tried it,,hehe ;)

[juiceclark]

Speaking of "high temp", I've seen two boats with dark blue hulls recently where the dark color obviously generated such temperatures as to further cure the fiberglass underneath. On one Grand Banks, the weave of the 2nd layer of glass was showing on the sides of the hull.
The third boat I've seen this on is my own - from being painted flag blue awlgrip. That hull gets so hot in the sun it has further shrunken the glass. So, looking down the side of the boat you can barely see where the bulkheads are...like a starving dog.

My point: you can become so technical with some stuff that the obvious can be overlooked - like the long term affects of your color additives.

[rwatson]

JC - Just reading sam devlins book on boat building- he has a whole section on how dark colours can 'melt' the epoxy, and create the printhru.

I would be surprised to hear that polyester or vynelester gets affected by heat, but I know that epoxy can be.

Would these boats have used epoxy on them?

[tinhorn]

Indeed they do, rwatson. Vinyl less than poly, and it can be reduced somewhat by using fillers. I observed less shrink with microsphere-filled resin. Hehe - an acquaintance (not knowing I was in the biz) once showed off his new boat with "metal mesh buried in the fiberglass for toughness. You can see the pattern!"

[juiceclark]

Well, my boat is a 1982 F-36 Trojan with "flag blue" awlgrip. In person, you can clearly see the fabric in areas of the sides of the boat. The hull is 7 layers of glass below the waterline and 5 above with no coring.

I hate the dark hull anyway - shows every damned drop of salt and dirt - but it sure looks good in pictures.
http://i246.photobucket.com/albums/gg120/juiceclark/CHorseNew-1.jpg

[the1much]

you guys dont think the reason you can see the fabric pattern is because the numbnuts that built the boats went to thin on the gel?,, like MOST boat builders do?

[tinhorn]

Wouldn't matter, man. Resin shrinks - 'glass doesn't. The better the 'glass/resin ratio, the less shrink you'll see. Of course, with chopper guns, you'll always be resin-rich.

Indeed - that boat is a beaut! Well, as long as it's perfectly clean, eh?

[ondarvr]

Back to the original question first. The questions are very difficult to answer because you want specific answers to general and wide ranging questions.The chemistry can be very different between gel coats, so they aren't always compatable enough to just mix together (most times they are though).

Adding different promoters, Inhibitors and using different catalysts can yield different results, some good, some bad.

Gel coats do not exhibit all of the properties of the base resins they're made from. In being made into gel coat many other ingredients are added, some improve certain properties, some degrade others.

Frequently more than one base resin is used to make a finished resin or gel coat, but you can't just blend any and all resins together. And this is only within a type of resin, not blending polyester with epoxy for example.

[ondarvr]

As for shrink and print through. We all see the dreaded post cure on dark colors, it is from shrink, but there can be many causes for the shrink.

Thin gel coat will show it to a greater degree, but is not the cause, the type of resin used, how it was catalyzed, the temperature it cured at and the resin to glass ratio are the main contributors.

Some resins shrink a great deal, others don't, so a resin designed to yield a good surface profile will help.

Using the correct amount of the correct catalyst to properly cure the laminte is very important.

If the exotherm of the resin is too low it won't properly cure and it will continue to shrink for a long time.

The higher the glass content, the more fiber print you will see, this has been a problem with infusion, the glass content is very high and surface profile can be poor. This can be overcome, but it takes more work than in hand lamination.

Print blockers of differnet types can be used to help reduce the print.

[fiberglass jack]

i find to help stop print through is to first skin the gelcoat with c-viel and one layer of 1.5 oz mat using vinyalester resin and make sure you put on a good 20 mils of gel, we all know you can get away with 12 or 14 mils but to stop print through you need a good layer of gel, the vinyalester skin will be harder then iso or ortho, and will be a good bairer for ossmosis

[ondarvr]

The VE used for the skin coat needs to be designed for that purpose, most VE's are somewhat sluggish in the cure department and will continue to cure for a very long time after demolding. Skin coat VE's are highly promoted to cure well in a thin laminate, which can make them difficult to use for the bulk laminate thats applied thicker. Like f/j said veil and a good 20 mils of gel coat help a great deal also. There are several types of spray on print blockers and other veil type products too.

[naturewaterboy]

onelemon (or whatever your name is):

you are looking for a gelcoat that you can put on some motor case that has to stand up to very high heat. There ain't NO gelcoat that will stand up to that temperature. I don't think there is any epoxy resin that will either. Sounds like you need a phenolic or some other material than what boats are built from. Any of the common boat building resins weaken really lots when they get a little hot - like at 100 degrees C, most resins will have less than 1/2 of their strength at 25 degrees (70 F). I'd say you need to look elsewhere for material - there are things like the cases of our grinders that are made from stuff like you are looking for.