Can you sandblast fiberglass to get a bond?

[222 ccp dgraf]

I am redoing my 222 ccp. My deck and all foam is out. Due to some cracks and concerns I plan to lay up two layers 1708 and one of mat on the entire inside bottom of the hull, including inside the stringers since the tops are allready cut off and the foam is gone. I am putting a lower deck in between the stringers down the center to set the fuel tank on and for the front storage area as well. This will be a lot of grinding to prep for this and some areas are hard to get to. On the areas that are hard to get to and the inside corners would sandblasting the areas work to get a good bond? Just to get rid of the gloss and ruffen the surface prior to laying up? Asked many but can't get a good answer from anyone who has ever done it. I am using poly resin, no epoxy. Thankyou for any advice.

[222 ccp dgraf]

wow I thought I would get some responses on this? I think I am going to do it. Makes no since why it would not work. I am laying up the entire inside of the hull on my 222 ccp including the inside bottoms of the stringers. The boat has a lot of dry lay up from when built and I will sleep beter with a couple extra layers on there. There are a few places that you can't get a grinder so blasting to loose the glaze and rough up the surface makes since. No one has any thoughts?

[fitz73222]

Ok I`ll take a stab at this one...
What kind of blast media are you going to use? Glass bead? Play sand? I think play sand would work best. (Sand box sand) I wonder if there are any issues with silica impregnation into the glass. The media may just bounce off the glass with little roughing up. I would make a simuation on the bench and see if the glass adheres to a surface that is prepared this way. I wonder if one of those long strand wire rotory paint strippers would work better. Not to be confused with a standard wire wheel.

I gave it my best shot!
Fitz

[dbiscayne]

Have done some sand blasting myself, mostly bottom sides of cars, and am sure it will get into every little crack & crevice in the boat.  That little gap thats so hard to get at along the inside edge of each stringer is gonna get some sand trapped in there forever.  Will that matter?  probably not.  And I think it'll rough up the surface enough to help, gonna make a hell of a mess doing it though.  The only problem I foresee is this- when the blast media hits something soft like the little bits of foam left in there it usually doesn't just rip it away & clean the area, the soft stuff kind of absorbs the hit & you're better off scraping that off then blasting the hard surface.
Why no epoxy?  It's pretty incredible stuff, shop around, I pay $38 a gallon here, and it sticks to things I really don't want it to.

I like fitz's idea, the long strand wire rotory paint strippers sounds like it'd work great.

[slvrlng]

I agree that its going to be almost impossible to get the blasting residue off the surface. This will weaken the bond especially with poly resin. My main concern having blasted a lot of car frames is the glass is relatively soft and the blasting would be very difficult to keep even. One softer spot and you could go all the way through! Here is a link to one of those wire wheel remover tools. I can't get the link to show the exact page so you have to search for it. The part number is 18253 and it is a bad ass son of a gun!

http://www.dynabrade.com/dyn09/content.php?page=catalog

[dbiscayne]

how 'bout a needle scaler?
http://www.harborfreight.com/cpi/ctaf/d ... mber=96997

[222 ccp dgraf]

Yeah my biggest issue is all the trapped media that will be under the tabbing on the inside of the stringer. All my foam is out and Have been working on grinding out the entire bottom inside of thre hull. There are a places that you just can't get any grinder or small air dremel. I do a lot of sandblasting as well and had planned on using balck beauty media which is very coarse. Just want to do this on the inside corners where I can't get.

[orb]

I would use epoxy rather than polyester. Epoxy adheres to dry surfaces much better than polyester resins. It is a little more expensive, but much better adhesion.

[Marcq]

There are a places that you just can't get any grinder or small air dremel.

If it's too small to fit a dremel, just use something to scratch that area, can't be big(the area), screw driver, fork, name it. I think a wire brush works best, like the battery pole wire brush, on one end it has a ball wire brush for the terminals, works well for thight places
I would not sandblass for all the reason mentioned above

About poly vs epoxy, why not use both, keeping the epoxy for strategic area, like where the transom meets the hull, poly for the rest

But still think epoxy is overkill

Marc..

[222 ccp dgraf]

well after about 60 hours grinding the entire inside of the hull I did a good cleaning and decided to try the sand blast route. I tried every media I had and nothing would etch the glass. Went down and got some regular play sand in the bags (like 3 bucks a peice) from Carter lumber and it worked great! Now keep in mind the only areas I did was the tight corners like the inside of the stringers and such. It took ma a few hours total and don't think that glass is soft as it takes a lot to etch it. NOW it took about 4 hours to clean up and get all the sand out! The good thing is sand shop vacs very easy. I am finally ready to start laying up the inside.