in mold painting - has anyone done it??

Hi
I have heard of a few companies experimenting with in mold painting instead of gelcoat. it would save alot of weight and provide a much better finish. process would be to spray the paint in first, back it with a light layer of primer, then withe a skin coat and laminate, or just straight laminate.
issue would seem to be the release agent. it needs to be able to release the paint, but also have just enough of a bond with the paint to allow the paint to stick on verticle surfaces. I have heard that a few mist coats of the paint prior to a heavy coat helps.

Has anyone done this before? can anyone provide advice? does it work? it is repeatable, etc etc. its not for all boat builders, but for high end boats or to save weight, it would be great.

your help is appreciated.

 

I have never heard of it, Other than in areas where builders cant find quality gelcoaters or to save cost, I would think there would be a few issues, biggest would be to keep it from fish eyeing I would think would be very hard, As far as getting a nice finish in gel, Is not that hard, I would rather have a high quality gel finish than paint it is much more durable, Paint would scratch very easy, imagine some sand on the hood of your car and wipe it off with a beach towl, As far as a quality finish a good trick is to spray each graffic with clear first then your fades and color and nice sharp pins, it makes your job much nicer as well as the quality and prep of mold prior to lay up, as far as a weight issue I dont think the amount of gelcoat weight is that much of a issue, if your looking for better performance on your hull you can always roll the hull over and make it perfect with no hooks or defects that could possibly cause drag and then speed coat your wet surface, JC

 

In mold painting

I've done it for years on large and small rc model yachts(see: www.microsail.com). The key is to use PVA and Partall #2 paste wax. Other waxes such as TR had trace amounts of silicones that caused fisheyes.There are new waxes out now that may work as well but I haven't tried them-no silicone based wax will work. The PVA has the advantage that it imparts no wax residue to the part. The technique I finally settled on was to wax the mold with two coats of Partall paste wax then POUR the PVA into a vertical mold with a receptacle below to catch the excess PVA. Then I allow the mold to rest vertically and slightly upside down for approx. one hour. When you're ready to go the poured PVA has a perfect,flawless finish equivalent to the best wax.Needs a very clean shop area for doing the pouring.I've used the old (and maybe still available ) formulation of Krylon which I tested experimentally and it-amazingly- works like a charm. I've used Imron as well-both these paints are very sensitive to how quickly you lay up on them-the window is between .5hr and 1 hr-any longer and the epoxy won't bond well to the paint. No need to use primer. For the smallest models this worked well because the customer could get touch up paint anywhere.The gloss is extraordinary with both paints provided you pour the PVA-don't spray it.
On larger models I've sprayed in a two part primer called Rober-made in Italy-works great and you don't have to pour the PVA-just mist it on . There are some new "in the mold" coatings-primers made with vinyl ester resin- by Duratec, I think; I have no experience with them. Using the method I described requires that you use epoxy resin to laminate the part.

 

there is a person that makes 12 foot fishing boats in monterrey mexico, and because he needs to keep the price down he paints the mold with polyurethane paint then layp the glass.
they pop up ready painted, they look and stand the use good enough ut not forever like gelcoat.