I would guess your going to have a fail. Once gelled its gelled. I think you could get away with brushing a layer of resin in the mould and apply dry fabric when it has gelled.

Fred

When doing a complex part that would need prepreg or profinish, what about wetting one layer of cf, leaving it down until just tacky, applying it in the mould with cuts and so on like with prepreg and then going on like for standard infusion with the other dry layers, bagging and infusing??
Anybody tried this?


Alessandro

Hi Matthieu

Doing it outside in the cold is a great idea.

So in other words our Canadian Eskimos are always using prepreg whether polyester or epoxy.  

Fred

Hi Fred, To be honest I haven't worked with prepreg yet. I'm making some moulds at the moment to test it out soon!

Hi Kev

I took a look at the forum that David Algie has.(Yahoo Groups LP1  he is the one in the video on how to make prepreg)

B-Stage means that the resin has partly cured at room temperature and to fully cure you need heat.

The stuff David Algie makes is not B-Stage, it is A stage resin, so not cured at all. So really his prepreg is wetted out carbon with the hardener in it and it will not cure without heat. I think he has a 12 month window before it will start to cure on its own. It needs about 250 Fah to cure in an oven.

He knows his stuff but I would be interested to know how wet the stuff is to work with. Prepreg in B-Stage is like using pattern makers wax sheets. Very controllable and holds its weave. Would A-Stage stay together?

Any knowledge from experience would be really welcomed. I don't know as much as I would like on this topic.

Fred

PS Just did my 5th EasyComposite prepreg attempt. Perfect results. The more I use prepreg the better I like it!!!!  

Hi,

Well what Fred is saying kinda makes sense, but I think this depends on what resin is used...

See This

Kev.

Hi Scott

I have talked to this fellow on a forum quite a few times. What I have gathered so far is that this home made prepreg does not go to a semi cured state like commercial prepreg. It is more like wetted out carbon with the activator already in it that will not cure until you bring it up to 250 f or more. So you put it in your freezer and you treat it like prepreg but it is a bit different. You definately would not handle it without gloves like the OPP Racing chick was doing.

Fred

CarbonFiberCreations

There is a youtube video of a guy who shows you how to make your own prepreg, he claims it is better than store bought.

Check "How to make your own prepreg" David Algie is his name. He was chief fabricator for a formula racing team. He is also making an all carbon fiber airplane. Its worth looking into, I have learned a lot from him.

I made an autoclave for $600.00 out of an old industrial sized paint pressure pot. It is 60 gallons large.   Good for 110psi

Fred

Indeed Pre-Preg looks really easy, and just like Leon said; It's quit hard to control the technique perfectly...they probably made a lot of tests and adjustments to get those perfect parts.