uhm anyone knows, if polyester and epoxy-resin could be used at once? For example: Polyesterresined outside(letting it sit, till hardened ), but epoxy-resined inside with fibreglass mats. Or is it possible that the resintypes would eat each other or something?
Curious, I was planning on doing just that myself because I am starting to hate the styrene smell :-D
You can combine them, but you can't mix the liquids or anything. You have to wait until the first one is completely cured before putting the second one on top of it.
Also, there are other things to consider.
First of all: Safety. Epoxy (or rather its components) can contain substances that cause allergies and other nasty stuff you don't want - and thin disposable gloves won't provide protection against them. If you plan on actually sticking your fingers into the resin (which is likely to happen when fibreglassing), you need to get chemical protection gloves. Which ones to buy is a bit more tricky, I'm still working on that myself, because apparently the official tesing procedures according to EN standards don't work for the stuff we're talking about and thus don't allow any conclusions about whether a glove is appropriate or not. From what I've read so far, butyl gloves thicker than 0.5 mm and some (not all) nitrile gloves work. Nitrile doesn't like solvents, though, so you can't use these when working with polyester resin, epoxy that contains solvents or acetone.
A second thing is that an epoxywon't work very well with fibreglass mats if it doesn't contain solvents (which is a good thing otherwise). The fibres in these mats are held together by something that is supposed to dissolve in styrene and in connection with epoxy the mat will just stay an inflexible mat.
Third thing, you probably know that already, but just to make sure: You need to stick to the correct mixing ratio, preferably by weight. The tolerance is very small here (like 2% or something). Unlike polyester resin, which is pretty forgiving when it comes to (especially too much) hardener, epoxy won't cure with too much or too little of it and small deviations will already result in a lower quality.
In porgression forums and videos i see many diffrent ways to resin and fiberglass. First to do the inside with lots of resin and fiberglass, then do the rest. The other way is vise versa. I see people with some inside supports, lots of inside supports, and sometimes even not at all. Can anyone tell my the safest way to resin and fiberglass? If it warps i have a plan B but i would do that on pourpose rather than accident.
Do not use fibreglass on the outside.
The best thing to do is use heavy cardboard (this has the largest influence) and use any pepakura struts that come with it. It you think it bends easily, put in some more (wood, paper, ...). Then brush on a thin layer of resin (and I mean really thin, use as little material as you possibly can), let it cure and then put on some thicker layers. One to three should be enough. Then take the struts out and start glassing the inside. Alternatively, when using Rondo or anything liquid, you can leave all or some of the struts inside until it's completely hard.
