need some help here for molding

ok i tried looking some of this stuff up and im kinda lost. i have worked with fiberglass itself before, and need some help on learning more then that. im making molds and have some done already. now im used to just fiberglassing it and spending lots of time with bondo and red glazing putty, can anybody advise me on gelcoating and other aspects of cutom making fiberglass pieces. id really appreciate it

can i use a paint gun to spray it on, where do i buy gelcoats. do you spray gelcoat into the mold twice with both coats being diffrent? i really have no clue and the bond job doesnt come close to how perfect the molds were. thank you all

 

Spyder, I am located on Long Island as well. There are a few suppliers of gel coats, resin and fiberglass on the island. Give Warren a call at Dynagrout, which is located in Deer Park. He will have what you need. To spray gel coat, you should use a "cup" gun as opposed to a spray gun. A cup gun has a larger nozzle than a typical spray gun. Generally, gel coat is applied in three passes, with a buildup of 6 mils per pass. You do not want to apply gel coat in one coat as it needs to degas a bit.

Let me know where you are located, and if I can get a chance, I can give you a hand.

 

thanks for the quick reply, im in coram so deer park isnt to far. how much is gel coat and is there any links to aticles on here on "how to use gelcoat" or "basics of all aspects of glass work" i read on here that the first coat needs to be mixing with 1 thing and the second coat needs wax added to it and so on and so forth. im even willing to work at night in a boat place to learn all about the proper process's.

 

If you are making a fiberglass part in a mold, nothing gets added to the gelcoat. The gelcoat is sprayed (it can also be brushed) into the mold. However, if you are gelcoating an existing fiberglass part, then you would add something to the gelcoat to make it easier to spray. Typically, you would use Duratech High Gloss Addative.

Due to the steep increase in the price of oil, resins have also gone up as well. The price of gelcoat will be dependent on the quantity you buy, but expect to pay around $50 a gallon. This is just a guestimate as I have not bought any recently.

What do you intend to build from the mold?

 

well im actually making a few diffrent things. custom engine hatch for my jetboat it had a 90hp and i put in a 120hp. the engine itself is higher so i have to fabricate a new one. im also going to be making some parts for my car. what happens if i used the resin for fiberglass and brushed it into my mold let it start to dry up and then added actually glass cloth and more resin? whats fiberglass reinfored plastic is that injection molding?

 

if u just coat the mould with resin it will fisheye and wont work, what you can do is use c veil which is a fine fiberglass cloth looks like tissue, this is mainly used for chemical barrier , best to use gel coat eagal is right use a cup gun but a primer gun will work with a 2.0 tip the thing about gelcoat it is not paint so any painting exp u have forget it, dont want to sound like a smart arse but have seen many painter in the past f@#k up with gelcoat, you need to get around 20 to 24 mils on if its a light wieght part as low as 12 to 14, any less then 10 u will have alagation wrinkeled gel on the finsh part, u want to get the gel on fast between coats with the first u will have 6 mils or so but if it starts to cure the next pass will softed the first and wrinkle it bad u will see it bubble up in front of your eyes, when u have a nice orange peel look you will have 16 mills or so but use a gauge to be sure, to much gel say in the corners which can build up fast on u , u will get pre release this is from to much heat in the cure and the gel will lift off the mould and is a ***** to fix, if your doing car parts use sanding gel its much easier to sand down but no good for marine use and coat the mould with pva u dont want wax on the part if u are going to paint

 

what i often do is just brush the gel on what u have to do is get brushing gelcoat its thicker then spray gel ,get the gel on and with the brush smoth it out by floating the brush try to keep the brush from touching the mould, you will want to do a second coat but make sure the first it dry the second coat has to be hot meaning it will cure fast so not to soften the first coat and wrinkle, this is because the styrenne in the gelcoat, some times i mix say 25% resin in the gelgoat to thin it down for the second coat, the thing is u are not painting, u are applying gelcoat which goes on heavy not thin like paint

 

thanks so far for the help guys, it sounds as if brushing it on i would be less likely to mess it up, the mold is small and has some curves and 90degree turns to it so i guess i should brush it on. is it stiff stiff like it wont run down from gavity it will stay put like tar? now brushing it on it will naturally dry fast on the second coat? and 25% resin you mean fiberglass resin? should i put a fan on it does that dry it faster? now i guess id let the second coat of gelcoat dry/degas for what a day or 2 then i can put glass over it? do i need to sand between the gelcoat and glass application? is there anything i could do to make it lighter/stronger other then addidng cf? can i add chicken wire? the last mold i did i used 4 layers of glass and it was kinda flimsy still. down the road when i get good at his id love to make a waverunner out of cf not for looks just because of the strenght/lightweight

 

yeah it will kind of tar like , use a fan helps remove the styrenne, once its dry you can put on the second coat this may only take a hour or so not days, no dont sand the gelcoat.

 

ok i went to where eagle said and went on a lil shopping spree. and i did as you said mr jack brushed it in and on the second coat applied some glass resin. ill find out tomorrow how it turns out. oh how many layers of glass should i use. this is not the final product it a bunch of little pieces going onto a bigger piece which is what ill be making my plug out of

 

1 Layer Of 1 Oz Chop Mat And Roll Out All The Air Just One Layer This Is Called Skin Layer After Its Cured That Is When Hard U May Lay Up The Next Stage Dont Go More Than Say 4 Layers U Dont Want Heat Build Up

 

well i checked it this morning and basically i think my molds are screwed. i sprayed numerous coats of the pva allowing it dry between coats as per the bottles instructions. and its not exactly releasing. basically the crisco 1 coat 5 minute process worked almost perfectly . how will gelcoat interact with crisco i know fibeglass had no problems. 25$ for a gallon of pva and 2 hours to apply isnt going to cut it when crisco is basically free and takes 5 minutes

 

ok i managed to get 1 piece out of the mold, why is both sides tacky. the gelcoat basically kicked right in my pan both times but its all tacky dry but tacky and i had a fan on all the pieces for 11 hours ? will this tack do away or was i supposed to add something to the first coat? can this piece still be used?

 

well i managed to get 1 other piece out broken into many pieces and took a long time to fix the mold, redid it the crisco way popped right out but had lil brush marks oh well. i guess ill have to hope the pva will allow me to pop out the rest of the pieces or ill just have to destroy the molds to get them out. i guess masonite needs alot more pva then the pva instructions say

 

ok new question for you guys.... how do i make a small rounded item like a pipe or car spoiler? and leave the inside hollow but perfect on the outside, this has really got me stumped, please advise