quick glassing question

[KCKracker]

i googled and couldnt find an answer, is it stronger to do matt over matt, or cloth over matt? also, i am still confused when to use matt and when to use cloth?

 

[joelybob]

Re: quick glassing question

what are you using for resin ? . you should only use polyester resin with csm.

 

[KCKracker]

Re: quick glassing question

yes i am

 

[mwe-maxxowner]

Re: quick glassing question

Mat is used when you are waterproofing, or don't need a great deal of strength. If you need strength, use mat, then cloth. There are different weights of cloth. Lightest weights are not very strong, heavier are stronger.

You might find biaxial cloth of interest. It is cloth, with mat already stitched to the back side. Saves some work and is easy to work with. Look at us composites.com for 1708. It is a strong biaxial cloth. Decently easy to lay. Strong! It is 17 oz cloth with 0.8 oz mat already stitched to the back side.

You should read some stickies at the top of this forum. GREAT fiberglass info there. Some of the restore threads are informative also.

 

[KCKracker]

Re: quick glassing question

ah jeez. i asked tyhis in my build thread and was told cloth was weak, use matt on the bottom side for strength.:facepalm:

 

[mwe-maxxowner]

Re: quick glassing question

Matt should be used on the bottom side for waterproofing. For a deck, the edges should be tabbed for 6-8" around the perimiter with mat and cloth, or a biaxial cloth alone, such as 1708. Then 2 layers or so of mat, each layer extending about 3" further up the hull than the last. A finish layer of a lightweight cloth can be used for appearances.

I don't know much about the chemistry of it, but somehow or another mat helps cloth bind to the wood. Without the mat, the cloth doesn't adhere very well, when using poly resin, and will delaminate in short order.

 

[jbcurt00]

Re: quick glassing question

To create a resin (polyester resin) rich layer........ It's intended to keep the sub-surface (plywood) or the 1708 from wicking the resin away from the other surface, which would starve that portion of the lamination of resin. And that could lead to delamination or poor adhesion between the plywood, the fiberglass &/or the resin. None of that would be good in a structural application/repair.

That's the 'reason' for using CSM before laying 1708 biaxial cloth. Depending on exactly what you're doing, stringers, tabbing, transom, deck, back-side of the deck, etc determines what to use & how to lay it up.

WOG's revised his graphic, to reflect that CSM is no longer REQUIRED (read recommended in all instances) prior to using 1708, only in some instances depending on what is being glassed.

Terms like mat vs cloth aren't necessarily accurate enough to describe the products you should probably be using.

CSM is a fiberglass mat, but all mats aren't CSM. The CSM referred to in most (almost all) threads @iboats resto forum is 1.5oz mat.

1708 is biaxial cloth (17oz biax w/ 3/4oz CSM stitched to the back) but all cloths are not biaxial

Your floor glassing question thread has a bunch of these details & WOG's graphic:

From his link:
"Fabricating Decks, Stringers, and Transoms"

If you are on an ultra tight low cost budget, you might want to take a day or 2 and read thru some info that's been provided & ask lots of questions. Lots of questions have already been hashed thru & posted in other threads. Reading some of them may help all this stuff make more sense, be easier to follow, and ultimately, when you start working on some portion of the resto, it won't be so frustrating & you won't 'waste' materials or time.

 

[Woodonglass]

Re: quick glassing question

ah jeez. i asked tyhis in my build thread and was told cloth was weak, use matt on the bottom side for strength.:facepalm:

No, I clearly stated that CSM was all that was required for the bottom of your deck and it is. Strength is not required on the bottom side of the deck, only sealing and waterproofing. The Top of the deck needs a bit of both. The Tabbing to the sides of the hull is the most critical point for strength and thus the use of the 1708 biaxial tabbing. Two layers of CSM will give more than adequate waterproofing and strength for the surface of the deck whether you're gelcoating, painting or carpeting.

 

[Woodonglass]

Re: quick glassing question

ah jeez. i asked tyhis in my build thread and was told cloth was weak, use matt on the bottom side for strength.:facepalm:

I have followed your othe thread very closely and don't recall anyone stating that cloth was weak. I did state that CSM was all that was required for the bottom of your deck and it is. Strength is not required on the bottom side of the deck, only sealing and waterproofing. The Top of the deck needs a bit of both. The Tabbing to the sides of the hull is the most critical point for strength and thus the use of the 1708 biaxial tabbing. Two layers of CSM will give more than adequate waterproofing and strength for the surface of the deck whether you're gelcoating, painting or carpeting. If you want a bit more strength then an additional layer of a 6 oz cloth can be added to the top of the deck. In two of my previous posts on your other thread I stated the need for laying CSM prior to Cloth in order to promote a good bond. If you're using 1708 then the CSM that's sewn to the cloth is adequate and additional CSM is not normally needed if the substrate is flat and smooth. I agree that slowing down and doing some reading and studying here on the forum would greatly help you understand the glassing procedure better.

 

[chconger]

Re: quick glassing question

Don't want to hijack, but its along these lines; is CSM nesessary if using epoxy to waterproof? Is it "bad" for any reason? (Got some kicking on my transom as we speak)

 

[Woodonglass]

Re: quick glassing question

Don't want to hijack, but its along these lines; is CSM nesessary if using epoxy to waterproof? Is it "bad" for any reason? (Got some kicking on my transom as we speak)

This would be classified as a HiJack but... CSM is not required for epoxy. It requires styrene to break down the fibers and epoxy has none. It will only act as an absorbent to the resin and built bulk to the structure and add nothing else.

 

[chconger]

Re: quick glassing question

Thanks (won't do that again (hijack or csm/epoxy)

 

[KCKracker]

Re: quick glassing question

so after i fillet the deck to the hull, and start tabbing, so i have to use 1708 biax? i do not have any and have not been able to find anyone near me that has it.

 

[jbcurt00]

Re: quick glassing question

Where is near you? KC: Kansas City?

 

[KCKracker]

Re: quick glassing question

black diamond, wa

 

[jbcurt00]

Re: quick glassing question

See my reply in your floor glassing thread:

There is likely at least 1 boat repair shop 'near' you that will sell you 1708 at a retail price off their wholesale rolls. You may need to dig to find it. But it may be cheaper to buy & you won't have to pay for shipping. Being able to swing by & buy a couple yards of 1708 when you run a tad short is a HUGE advantage too.

^^^ condensed version.........

 

[ondarvr]

Re: quick glassing question

Nothing is "near" Black Diamond. Fberlay will have everything you need, but it's in Seattle. Talk with Dave if he's in.

1708 works great, CSM and roving works well too, many combinations will work, some just a little better than others. Steve Ericsson has what you need, not sure how far he lives from you. I gave him a bunch of stuff for Wannafish

 

[KCKracker]

Re: quick glassing question

oh that was you lol, steve already offered me some 1708 but have not been able to reach him easy, we chatted on FB shortly last night he asked me how much i need but have not heard back. so i figured id just go buy it instead of bothering him lol my tabbing will be a total of 22' long each layer

 

[Yacht Dr.]

Re: quick glassing question

ah jeez. i asked tyhis in my build thread and was told cloth was weak, use matt on the bottom side for strength.:facepalm:

Cloth is Weak !! Then again .. what Cloth do you speak of

Some good info on this thread ..

One thing that everyone should keep in mind ( and it was brought up in this thread already ) is the Weight of the "Cloth".

You have to understand that those of us that work with fiberglass everyday have different terminologies than those that are used in open DIY forums.

We Glassers have to re-train our definitions sometimes to understand what is being used. ( We/I see an expression and we/I shoot it down as being the wrong product just on wording alone )

"Cloth" being a good example.

In the Shop we have all sorts of Fiberglass materials at our disposal. We even have our own language for each type of fiberglass/fillers/grinders etc.

When the word Cloth is used .. it means a light fiberglass mesh that is used with epoxy for Surfboards.
When the word Mat is used .. it means .. 1.5 oz CSM. At least we all agree on this one
When the word Fabric is used .. it means any other type of Structural fiberglass weave. ( 1708/woven etc. )

As you can see it really depends on how a generic term for fiberglass can sometimes be misunderstood. When someone suggest that Mat is stronger than Cloth .. well that could be correct depending on what cloth your using. But if cloth means 1708 then no .. mat is not stronger than the cloth your thinking of ..

I hope this helps develop an understanding of how important is is to use more specific product definitions other than "Fiberglass and putty" because there are so many types and uses for each product(s) and conditions.

YD.

 

[KCKracker]

Re: quick glassing question

west marine.."sorry we do not stock cabosil, we can order it but not stock it, nobody ever uses that stuff".... :facepalm: i guess im going to fiberlay up north.

so another question, where my deck sheets of plywood meet, do i glass that seam before i glass the whole floor? if so what do you recommend for the seams? anything special?