so im reading the post that seppuku posted about mold making, and i was hoping someone could clarify some things for me...cause let's just say that i tried just taping off an area and fiberglassing it and pulling it out, and it was ROUGH ended up breaking a piece off on accident, actually, but i patched that up



but anyways, i'm sorta confused about the details about how this "molding" process works.



first he says you'll need some wood or something to stiffen the mold before releasing it? that confuses me



for the process, he says to polish the part. well, i'm confused, because the part in question (the back seat area, where i pulled out the seats) is a very imperfect surface that still has the factory noise-dampening material on it, so i can't "polish" it (at least, not polish in the terms im thinking, like you would to your car after washing and waxing). maybe this is just a rub on, rub off sorta compound that i use over and over?



next he says to spray tooling gel coat...okay, sounds simple enough, since he says you also gotta go get a sprayer for it..check.



then put a layer of 3/4oz matting...then 1.5oz matting? wait wait, where's the mold? this just sounds like this is what would come out of the mold AFTER i had a mold to use?



ok, even after that..he says "add stiffeners." umm..add wood? where? how?



i'm sorry if these sound silly, but i feel like i have a decent understanding of how fiberglassing works and this is really confusing (now that i want to get into making molds)

 

1. The mold that you will create will most likely be thin since it is fiberglass so you use wood to stiffen any of the sides that can flop around. Also, it will just help to keep the molds shape as you cast parts from it. This determines how well your final piece will fit as well as how long your mold will last. To reduce the amount of supports you will need, you can reinforce your mold with honeycomb board, Styrofoam board, or even spray Styrofoam works.



2. You need to polish the part you are going to be creating the mold from because your mold will have to have a releasing agent applied to it so that the part you are casting will pop out of the mold. Any tiny pore or scratch that you have in your negative will show on your casting. Plus, the bonding agent that you use may adhere to larger scratches and rough surfaces making it almost impossible to release your casting.



3. This is what a lot of people don’t understand about mold making. You need to make a negative casting of the part you want to make first. Then from the negative casting, you will create positives, which will be the parts you will use. So basically, you need to make the opposite of the part you want to create, and then make the part. Again, this is another reason that you want to polish your part that you will be making the mold of. The more prep work you spend in the beginning means the less work you will have to do finishing it. So less sanding, which is good because sanding fiberglass sucks.



This is the same concept for almost every other technique used for making molds, be it metal casting, injection molding, etc…

 

thanks for some clarification...so would i be correct in that the "polish" is more of something i can rub on any surface, not just metal (in this case)?



the wood confused me because i wasn't sure how to apply/attach it to a surface that isn't ever flat, but when you mentioned even using spray styrofoam, i think i understand its purpose now.



the hardest part for me to understand is that even though i'm "filling in" the back seats with this stuff, when i put the fiberglass on the mold again, it'll still be the same thing.



again, thanks.



actually, one more thing...can anyone recommend the specific products he lists that work well for them? ie: releasing agents, gels, etc.



for this project, i figure i could just roll the jell on without the sprayer, as roll marks won't really bug me (but they will, say, when i try to mold things like body panels).

 

Polish would be the action of smooting the object that you want to make the mold from, basically, just sanding it down to make it as smooth as you can, be it metal, fiberglass, plastic, etc...



With the wood or metal supports, you can mold them in to the mold that you are making when you are building up your layers. Normally, you would lay down a few layers of fiberglass on your object, then your supports, then more layers of fiberglass. Most people use wood becuase it is cheaper, but moisture and time will cause it to deform. Spray foam would go on the exact same way, lay a few layers of fiberglass, spray the foam on, put a few more layers of fiberglass, but depending on your molds shape, you still may need some wooden supports.

 

oooh, ok, awesome hooray, im gonna get a list of stuff i need to get to start and order it all at once; that site listed in the faq seems like it has everything