[cashxdr]

I have been reading these threads and just wanted to make sure I was on the same page as everyone else. I have been a aerospace composite guy for about half my life and was a little confused on some of the terms being used.

I have seen basically two terms used, wet and dry and was wanting to be sure the definitions. Seems dry has no shine and wet has a high shine.

In my background, we add peal ply to the outside of a layup in order for secondary bonding. Basically so we do not have to sand. (only in low G situations) because in composites, when it comes to bonding, if there is no shine, you will be fine. You can do this with either wet layups or prepreg. The look of this type of layup seems to be what you call "dry" and is ready to bond without sanding and has no shine

Your "wet" layups seem to be when you increase the resin on the outer layer, weither it be adding extra raw resin or a extra layer of pure resin prepreg to increase the gloss and to give a extra shine or it has been done in a zero loss closed mold and autoclaved. There is no proper name for this other than just laying up directly on the mold.

I guess the other question I would have is are the parts autoclaved, vacuum bagged or just layed up wet?

Just a little trivia for you, Burt Rutan did not believe in vacuum bagging when he designed the Long Ez. He got over it of course. heh heh

Darrin

 

[hackzi]

My understanding is....

Dry = prepreg autoclaved
Wet = wet-laid, oven cured

And for either of the above, you can have matte or gloss/lacquered finish.

 

[Thomasio]

People commonly misuse the term "dry" in the forum.

 

[Vishus_1]

Not to hijack this thread - but I have some carbon fiber questions...

As the owner of a new 260 - I am wondering what to do about some of the carbon fiber peices. I know the exposed exterior peices (mohawk, side vents, splitter, wing) seem to be cleared - so I think regular car polish/protectant with UV inhibitors will work for that. But then there is the interior, which looks like raw carbon fiber mat - there is no clear on it. Is there anything I can or should do to protect it?

I am thinking Armor All or any vinyl protectant would be bad. Is water/mild car soap bad? And even if it is ok, it won't protect it from UV sun? Will the dash just deteriorate if it has no protection? Even the sills are that way.

 

[Thomasio]

Not to hijack this thread - but I have some carbon fiber questions...

As the owner of a new 260 - I am wondering what to do about some of the carbon fiber peices. I know the exposed exterior peices (mohawk, side vents, splitter, wing) seem to be cleared - so I think regular car polish/protectant with UV inhibitors will work for that. But then there is the interior, which looks like raw carbon fiber mat - there is no clear on it. Is there anything I can or should do to protect it?

I am thinking Armor All or any vinyl protectant would be bad. Is water/mild car soap bad? And even if it is ok, it won't protect it from UV sun? Will the dash just deteriorate if it has no protection? Even the sills are that way.

PM Mike at Prototype Composites ("Composites" here), he's the guru.

 

[knucklehead]

I'm not the Guru as Mike is, but maybe I can clear a little of the confusion since I sell CF products for TWRD.

What's caused some of the misinterpretation is that there are two finishes wet and matte. As well as two process types pre-preg which has naturally dry finish and wet laid. Both processes can then be sprayed or coated with a clear coat for a wet finish, but usually for racing pre-preg is usually not, because the extra coating adds weight.

Hope that helps.

Jacob

 

[Thomasio]

I'm not the Guru as Mike is, but maybe I can clear a little of the confusion since I sell CF products for TWRD.

What's caused some of the misinterpretation is that there are two finishes wet and matte. As well as two process types pre-preg which has naturally dry finish and wet laid. Both processes can then be sprayed or coated with a clear coat for a wet finish, but usually for racing pre-preg is usually not, because the extra coating adds weight.

Hope that helps.

Jacob

Don't forget about vacuum infusion, which is lighter and stronger than traditional "wet" layup.

 

[fitfan]

Don't forget about vacuum infusion, which is lighter and stronger than traditional "wet" layup.

yes, but my understanding is that vacuum infussed is still technically "wet" as it is not prepeg. it is just a different technique of wet application.

if a raw wet layup comes out glossy - too much epoxy was used, a good wet layup should come out fairly mat looking. the "denser" the composite, the stronger - hence "denser" = less expoxy.

anything can be shot clear gloss or even finished with a coat of gloss epoxy. at least thats my fairly limited exposureto carbon/kevlar composits

 

[knucklehead]

My bad, I was just trying to explain the confusion of wet vs dry and wet vs matte. Not necessarily the properties of any of the CF processes.

 

[Vishus_1]

Ok but how do you protect carbon fiber - or do you need to if it is not cleared? Do I need to do anything with my cf dashboard and sills to protect them or will they deteriorate from UV?

Anything? :shrug:

 

[MaineLotus]

People commonly misuse the term "dry" in the forum.

Yup, that's correct. Dry carbon is a bit of a misnomer.

Carbon 101:

Dry carbon is prepeg - pre impregnated with activated resin and usually stored in cold temps to prevent the resin from setting. Most prepegs require an autoclave (oven) to cure. During curing it can be vacuum bagged to remove excess resin. Prepegs are typically very resistant to heat when fully cured.

Wet layup means that layers of cloth are saturated by resin, either by hand or with infusion techniques. During cure, a 'wet layup' can also be vacuum bagged and it can also be autoclaved to speed the cure process.

Neither technique has an effect on finish. I've made 'wet lay' composites that can't be differentiated from prepeg. Contrary to popular belief, wet lay with vacuum bagging is almost as light as prepeg with vacuum bagging. Another myth is that wet lay composites with the same layers of carbon are weaker than prepeg - not true. Excess resin does not weaken a composite, it actually provides *some* strength.

All laminates (not just carbon fiber) should be clear coated to prevent UV damage, clear urethane works well.

 

[knucklehead]

Ok but how do you protect carbon fiber - or do you need to if it is not cleared? Do I need to do anything with my cf dashboard and sills to protect them or will they deteriorate from UV?

Anything? :shrug:

My guess is that Lotus has finished the CF with a UV protective coating. BUT that is a guess and you should contact either your dealer or Abe on this forum.