Hello,
So i have made o mold using the high temp rated resin from easy composites of a sadle. I intend to use this mold for production of
prepreg Cf sadle . The cure temp will be up to 120 celcius.
I have done a lot of sanding to the mold ( 400,600,800,1200,2000,2500) and then some buffingh and the surface is quite ok but not as firm as it is with a clear coat on . Is there any clear coat i can apply that can handle 120 celcius ? I tried to do some clear coating with the same high temp resin that i used for the making of the mold but i got a lot of pinholes which resulted in the need of sanding which got me in the same point where i started. What can i do ?
You have to change your curing cycle. To get a pinhole free part an In Mould will not help you. You will have the pinholes below the IMC.
I have tested now several OOA prepregs, but I got with no one pinhole free results. The one from Axson and from User Prepreg (SPM)are good. The one from Axson is very simple in handling, put vacuum on it and temperature and it work well, but it has a blackened resin and will leave micro pinholes.
The one from SPM is more critical in the curing cycle, you have to figure it out but than you will get nice parts with only less pinholes (really few, nothing dramatic)
I always feel one of the goals in making a mould is to produce one that does not get any sanding. Sanding your moulded surface can only chance cutting into porosity within the surface which can lead to stickups repairs etc.
For me new moulds should only be polished.
What i am trying to achieve now is make the mold as close to perfect
Surface as possible so that it will create a fine finished part that will need as less treatmend as possible.
Thisi why i was thinkng if of a gel coat
agree with ddcompound, with our ooa prepreg pinholefree (or very very few pinholes) possible. the main factor is u have to know how ur oven works and how accurate is. and also some peope make mistake as instead of following/controlling the mold temp. they only look out for oven temp.
Interesting that nobody seems to be able to replicate the results that the Easy Composites ‘Easy-Preg’ system gives so easily. I know there are OOA pre-pregs that work well, but require a very accurate cure schedule. The Easy-Preg system can simply be thrown into the oven at 80 and left there overnight, and always gives consistent results.
The easy composites system is a system that is sold under several brands. An even there you will have pinholes.
Hey DDCompound,
What other brands is the easy composite system sold under? anything that’d be easier/quicker to get in the US?
Thanks!
I know Easy Composites sell the VTF 261 under their own brand but I dont know anyone else selling it under any other brand…
I have used VTF 261 too and it is good but not prefect if you do just cure it at a standard single temperature. It does need a curing schedule too for the best results.
I know it looks good out of the mould but as soon as you lacquer it you find there are issues. I now use SHD’s DF212 material and it genuinely is pin hole free if you follow a specific curing schedule.
Ok great, thanks! I’ll take a look. Do you think that just using a thin epoxy film, like the type used to bond nomex to prepreg, would have a similar effect as the special one-sided prepregs? I have made decent structural prepreg parts of non- ooa prepregs (they were significantly cheaper than OOA ones), but the surface finish left much to be desired as far as pinholes. Also, would it be a bad idea to use a prepreg like this for only the surface layer, and then use a different system of prepregs for the rest of the part?