Zip fibreglassing

keithhills · **Posted:** Sun Aug 12, 2012 2:47 am

After some time busy with work, we all have to do it occassionally, I am now ready to fit the bottom planking and think about the fibreglassing of the hull.
On reading the "How to Fibreglass Boats" and the forum I am a little confused about what glass to purchase.
I would like to use a bi-axial mat in epoxy resin, which I was going to apply by the dry method, therefore not encapsulating the plywood first.
Would anyone care to comment on what type or weight of bi-ax to use and fixing this straight onto the base plywood, or any better suggestions based on their experience.
I have attached a photo of where I am up to after 162hrs.
Keith
p.s. I crawled under the hull today to check that everything looked in order and cant believe how big it looks. Can't wait to turn it over!!!!

Roberta Hegy · **Posted:** Sun Aug 12, 2012 6:49 am

Planking looks very nice!! You really don't need to use bi-axial cloth. Regular 6 oz cloth will work just fine. I sealed my planking with a coat of resin the night before I applied the cloth. It helps hold the cloth in place, as it is a little tacky, and prevents resin from soaking into the wood and starving the cloth. It also enables you to position the cloth and smooth out any wrinkles. Then I mixed batches of resin, poured them onto th cloth, and spread the resin with a 16" window squeegee. Using only the weight of the squeegee, I spread the resin over the cloth, being careful not to overwork the resin or pull the cloth. Once the first coat of resin has set up to green stage (semi-hard but slightly pliable) I trimmed the cloth and began applying subsequent coats of resin until the weave was filled in. Recoating within 24 hrs (with most resins) there is no need to be concerned with blush and you will get a good chemical bond.

I used as slow hardener to prevent the resin from firing off too soon.

Roberta

vupilot · **Posted:** Sun Aug 12, 2012 11:01 am

You work fast. It took me 227 hours to get to that point!

Yes like Roberta said, a 6oz fiberglass cloth will work very well. You said Mat and I always pictured mat being the stuff with random strands where the cloth is woven perfectly. I used the glen-l cloth on the bottom which I think is 7oz and 4oz on the sides to ensure it would be crystal clear for the bright finish.

I encapsulated with a couple coats first and after removing the blush and sanding I then laid the fiberglass and I really like that method. I think applying the glass on a bare surface sometimes can leave you prone to spots that are epoxy starved and end up showing the weave as the bare wood continues to absorb the epoxy after you have compeleted the job and walked away leaving it to cure even though it looked plenty saturated before. I think encapsulating first makes the process more consistent, at least that has been my observation fiberglassing my two boats.

Your Zip is looking fantastic!

keithhills · **Posted:** Mon Aug 13, 2012 6:32 am

Thanks for your thoughts.
I glued on the starboard side bottom panels today and will do the port side tomorrow. Then I will go and see the fibreglass suppliers and see what we come up with in cloth.
I will definately encapsulate the hull just before laying the mat, that way I should not have to sand or wash down.
It sounds like it is OK to put more than 1 layer of resin on to get rid of the mat print, rather than 1 thick layer, so I will go that route.
Should be interesting!!!!

jprice · **Posted:** Mon Aug 13, 2012 6:39 am

I haven't used mat, only cloth.
But yes, you use multiple coats of epoxy to hide the weave. The first coat should be just enough to bind it to the surface, then subsequent coats are used to fill.

Just curious, why are you going with mat over cloth?

vupilot · **Posted:** Mon Aug 13, 2012 9:36 am

Just make sure you remove the Amine blush from the epoxy after cure before starting a new coat.

keithhills · **Posted:** Mon Aug 13, 2012 2:42 pm

Jeff
I hope I have the terminology right here. What I am going to use is properly woven bi-axial material because of its added strength. I have always called it mat, but I might be wrong?
I will read about this but briefly how do you get rid of Amie blush?

jeffh · **Posted:** Mon Aug 13, 2012 2:49 pm

I used biaxial glass for structural integrity in my enlarged transom knees. But that stuff would not be the best thing on the hull unless you are painting it. I think that stuff will hold more epoxy and if you use it on your entire hull, the weight will increase. How much, I don't know. I can tell you I was surprised at how much heavier my kayak got after glass and epoxy were added. The bottom would be the only place I could see using biaxial glass. I believe I would stick with what Chris suggested. Also, if amine blush is a concern, just buy an epoxy such as MAS and MAS slow hardener.

rbrandenstein · **Posted:** Tue Aug 14, 2012 7:15 am

Amine blush feels like a waxy coating on the surface.
I used warm water with some ammonia and a scrubbing sponge (has the non abrasive green mat on one side). Just scrub it down and wipe it dry. Not a big problem.

vupilot · **Posted:** Tue Aug 14, 2012 7:24 am

Amine blush is a by product of the epoxy curing process and is a waxy film. Obviously, thats not going to help the adhesion of anything you want to put on top of it so you must remove it before putting more epoxy or paint, varnish etc over it so you get a good bond.
Water and a sponge or cloth works fine but in my experience it takes 2 or 3 wipe downs to get it all clean. Some epoxy brands like MAS epox do advertise that it doesnt blush but I used it on my kayak and it still can blush in the right condtions, so you still have to watch for it.

jprice · **Posted:** Tue Aug 14, 2012 7:32 am

keithhills wrote:

Jeff
I hope I have the terminology right here. What I am going to use is properly woven bi-axial material because of its added strength. I have always called it mat, but I might be wrong?

Yeah, the woven bi-axial stuff is a cloth, mat is just chopped strands pressed into a mat.
But it still sounds like overkill to me. What's the weight of this bi-ax cloth you're going to use?

Also, I'd recommend reading the epoxy book from SystemThree. http://www.systemthree.com/reslibrary/l ... y_Book.pdf
Yes, they refer to their products, but there's a lot of good info in there that applies to all epoxy (there's also a section on fiberglassing).

jeffh · **Posted:** Tue Aug 14, 2012 8:14 am

The biaxial glass I used looks very much like the interwoven glass that everyone uses on decks and hulls. That pressed stuff is also referred to as biaxial, I think. Here is a link to some biaxial stuff.
http://fiberglassindustries.com/knitmat ... nAodKksAgw
http://www.jamestowndistributors.com/us ... fiberglass

Buckeyesmith · **Posted:** Tue Aug 14, 2012 12:56 pm

You should go with 6oz cloth on the bottom and 4 oz on the sides.

I have seen a type of biaxial mat called 1708 which has 17oz of strands with 8oz of chopped strand backing for a total of 25oz per square yard. That is way too heavy for your application and I doubt you would ever get a great clear finish with it.

You shouldn't have to worry about blush if you follow Roberta's method of applying the glass while the epoxy is still tacky. If you let the epoxy fully cure you should follow Chris' directions.

One caution that hasn't been mentioned, be careful to not put your first coat of epoxy on too heavy, especially on the bottom. It can "float" the cloth away from the wood and create a void that will never finish properly. After the first coat has set up you can apply the epoxy as heavy as you want. Just don't create a bunch of runs, you will find out quickly how hard they are to sand out.

Roberta Hegy · **Posted:** Tue Aug 14, 2012 2:03 pm

I'm not sure what Biaxial cloth is like, but if you are referring to bias cloth or bi directional cloth, you will not need this. Bias cloths are helpful where the contours are more extreme and you need the shaping/molding characteristics of these cloths to pull them over sharp bends or lay them into concave areas. The regular 4 and 6 oz. cloths that Glen L sells are perfect for laying out on the boats and will conform well and be invisible once properly laid out. Remember, you are laying this up on plywood, so contours are essentially cones due to the design Glen L built into the boat. Save your money.

Roberta

Bill CNC · **Posted:** Tue Aug 14, 2012 3:18 pm

IMPORTANT NOTE:

***** CSM = Copped Stranded Matt, ... and is not made for epoxy, it is made for Polyester Resin. *****

CSM is held together with styrene. The Styrene in the resin dissolves the Styrene in the Matt letting the individual strands move and conform to shapes. If you use epoxy, ... it WILL NOT CONFORM to any shape except using it on flat surfaces WITH NO BENDS.

HOWEVER, ... MATT can be used with epoxy for flat panels ONLY. It can be used in sandwich wood layups such as in building a HD transom and such.

1708 Biaxel Matt is WAY TO HEAVY for these little boats. It soaks up resin like a sponge and is EXTREMELY HEAVY. It is used when you want to add BULK to a layup or making molds.

Bill
who is playing the PSA Announcer :wink:

Glen-L.com

Zip fibreglassing

Who is online