Poly vs. Vinyl Resin

[patr1707]

I am currently re-coring the decks on my boat and have a choice to make, would it make sense to spend the extra money to get vinyl ester resin to rebed new core material then laminate a new top skin on it or save a couple dollars and go with polyester? I heard that vinyl ester has a tough time sticking to old and aged layers of fiberglass, is this true for poly too?

What are the pro/ cons for each besides the cost. Would it be that much better to do it in vinyl ester?

Thanks for the input!
Pat

[fkittson]

If you can afford the extra money go with vynel

[fkittson]

Sorry hit send to soon. Go with vynel if you can they both will stick with the proper prep. Vynel is a lot better for water tightness
Best of luck.

[sailvayu]

Vinyl ester has a better elongation than polyester and about half that of epoxy. It also has a better moisture resistance. It is more compatible with polyester than epoxy. That said I think in this application I would go with a GP polyester as it is more compatible with the resin you are bonding to and there is no really need for the improved properties for your application. I would use a polyester core bonding putty to bed the core in and then laminate with the GP resin. Check with your core supplier for the proper putty. mix it correctly and pay attention to proper application temps. Some will say epoxy is the only way to go but almost all pros will do the above. Good luck and post some pix

[sailvayu]

oh and good prep is the key to good bonding, grind all surfaces to be bonded with 36 grit

[patr1707]

Thanks for the info!

Here's some pics:

[sailvayu]

Looks like a good sized project. I would defiantly use the core bond to set the core in. Trowel it on with a notched trowel then set the core in. Use a vibrating roller (you can rent one) to press the core down. then fill in any gaps or voids between the panels with more core bond then smooth down. You will then have a nice smooth surface to glass over.
ATC Formulated Polymers Inc.

[patr1707]

Quick question, when using the core-bond b70 it says to prime the back side of the foam before laying it, is that with resin or the bedding putty?

[sailvayu]

Catalyzed resin also known as a "hot coat"

[fkittson]

The best way to do it is brush roll or spray on a medium coat of catilizes resin and let it start to kick (No transfer to gloved finger). Then spread thickend polyester resin with a 1/16" vnotched trowel and press core into. If you have access to vacuume bag equipment that would be best for the bond to pull all air out for the best bond. Fallow with whatever glass you are using. Min 4 layers of alternating 10oz. Cloth and 10oz. Stitched mat.

[sailvayu]

Be easier and better to use 2-3 layers of 1808 bi axial on a 0/90 bias for the top laminate. Almost nobody uses cloth anymore and it is hard to wet out and apply. Vacuum bag is good but you will get decent results with a vibrating roller, easier for home builder type application but if have access to the pumps, hoses, films and such it is the best way to go.

[patr1707]

Im got 1700 biaxial and 1'5 mat to lay up the top. I would see it almost impossible to vaccuum bag it in place... Ill look into a vibrating roller.and heavy weights to put on top of it...

[sailvayu]

the 1700 and 1.5 is fine, you could use a rubber mallet to help set into the putty as well. place the weights as needed and then tap firmly but not too hard with the mallet to work the putty into the voids.

[Nicholson58]

Originally Posted by patr1707

I am currently re-coring the decks on my boat and have a choice to make, would it make sense to spend the extra money to get vinyl ester resin to rebed new core material then laminate a new top skin on it or save a couple dollars and go with polyester? I heard that vinyl ester has a tough time sticking to old and aged layers of fiberglass, is this true for poly too?

What are the pro/ cons for each besides the cost. Would it be that much better to do it in vinyl ester?

Thanks for the input!
Pat

I have done a lot of glass work including bottom job, deck recoring, new rudder. I buy all materials form US Composites on line. I use their microballoons in a 635 epoxy slurry for all cores. It is absolutely waterproof forever. and very strong. I am sure you could also use their other resins. The resin you use above water is not so important regarding water & blisters. I was once warned by a technician that poly and vinyl should not be mixed but that epoxy will bond to either. If your boat predates the switch to vinyl you can be confident that PE will work. This is available cheap at Home Depot. US Comp. aslo sell glass, kevlar, carbon fiber. I have found their prices usually better than other sources. Fiberglass , Epoxy , Composites, Carbon Fiber - U.S. Composites, Inc.

The 635 thin resin has no amine blush so you can do successive coats without special prep. It can be pretty well cleaned up with soap and water before it begins to react. Reaction time is very slow.