A question on molds

I’ve seen the fiberglass mold being used most often in what I’ve looked up on Carbon fiber work. How many times is a fiberglass mold useable? If I only do 4 layers of fiberglass on a mold, will it be weaker than one that is 6 or 7 layers? What sort of steps could I take to ensure a mold will last a good long while?

Thanks in advance.

the easiest and cheapest method is making a mold with a poly or vinylester tooling gelcoat sprayed on, then laminating with chopped strand mat with poly or vinylester resin building thickness up to 1/4" to 1/2" or more depending on your size mold and shape. you can easily make a mold in a day. you can easily get 100-1000 parts off a mold before repairs are needed depending on the part and how well you maintain them.

hojo is correct and the most important layer is the gel coat skin and getting it on thick enough as that is your main mold layer. If it is rough, all your parts will be rough…

If you have to sand out an imperfection…and you don’t have enough gel coat on it…then you get into the reinforcements and you don’t want that