Differences within polyester, vinylester resins

Im wondering if there are major, or minor for that matter, differences within the various polyester resins and vinylester resins on the market today. What makes one "better" than the other? Please note Im not asking what is better poly or vinyl. Im wondering within the respective resins, what potential differences are. Im really trying to select a brand of each kind of resin for an upcoming project Im working on launching.

Also, how does one qualify what brand is better??

Thanks
James

 

Viscosity, curing temp, pot life.

If you purchase products intended for amature boat builders ...

The differences of importance will be in wet handling properties not in cured properties.

 

If your are making something that will take more stress, and possibly flexing then Vinylester has an elongation percentage that is much like epoxy, and much more than polyester. The elongation percentage of Vinylester will match the elongation of E and S glass. Whereas, polyester will fail much sooner because of its lesser elongation percentage. The viscosity of vinylester can be like that of polyester if that is the chemistry, pot life can be adjusted to by the maker. But viscosity, gel time, hdt are all in the hands of the maker. What should you get? That depends on what you are making.

 

If one looks at the physicals you will find the Vinyl Ester at nearly twice; Example on Tensile strength the polyesters are say 6000 (resin crumbles before glass is fully loaded) and the Vinyl Esters are around 11000..Also little things like secondary bonding a big Plus there.. But there is a drawback they cost nearly twice also. For the Better resins.

Elongation was mentioned before; the more sophisticated resins more closely match glass fabrics in this area. Also HDT is better and shrinkage is much less...

 

more on differences within the various resins

This is good info, thanks. You and the others touched on a good point: resins for amateurs, or resins for high stress boat, better resins. Im trying to find out how I can tell if a resin is high quality or low quality, or for amateurs. Im going to be building coastal cruisers and they need to be built to take fairly serious punishment. Im not interested in using low quality poly, or low quality vinyl. Im likely going to lay down most layers with poly and the final with vinyl. But... what quality brand of each to use... If I search there are quite a number of different companies selling resins. Im assuming the price will reflect quality, most times. Id rather not assume however. Im also building vessels that peoples lives will depend on, mine included. This is not the place to be cheap. So Im asking the community here for some recommendations.????

Thanks
James

 

The worst punishment these things can get is sitting in the water 24/7. Think about "tank coating", that is laying up the first few layers in vinyl, then switching to poly for the interior layers. You get the benefits of vinyl on the outside where it counts, especially blister resistance, and save the cost of going completely vinylester.

 

James,

You said.... "Id rather not assume however. I’m also building vessels that peoples lives will depend on, mine included. This is not the place to be cheap. So I’m asking the community here for some recommendations.????"

Here is something that might help you; calculate the total cost of the boat, then figure out the difference in percent of how much more it would cost to have the best resin (epoxy). It will be a smaller percent than you probably think.

It sounds like you are building a large boat, which means you should be able to get a pretty good deal on that quantity of epoxy.

Joel
boatbuildercentral.com

 

In my searching for resins and prices... I have found that Epoxy is about five times the cost of Vinylester... and not much stronger.... vinylester closely resembles the properties of epoxy such as water resistance and strength... but at a fraction of the cost.

 

For everyone who wants to know more about the differences between resins (and lots of other good stuff) Irecommend this book, now out of print but far and away teh best primer for fiberglass boat building!

Author: Sleight, Steve

Title: Modern Boat Building: Materials and Methods (224p)

Publisher: McGraw-Hill 01 January, 1986

Location of Book: U.S.A.

 

James ---

you wrote: "Im assuming the price will reflect quality, most times."

Price is not the correct measure. You might want unit_price/unit_strength.

It might be possible to use more of a cheap resin (in addition to more cloth) and produce a better product than using expensive resin.

Usually you do an analysis to determine what strength you need and then you look at the possible material choices.

 

...I'd sum your equation up as a '''strength to weight' issue.If you're trying to make a LIGHT,sturdy boat,,then the better quality resins should definetly come into play more,,but otherwise,,definetly do outside layers with vinyl resin for osmosis protection,,and then a lesser resin would be fine for most projects,,unless,as I say, you are trying to maximize on the weight factor!
Ortho resin,the cheapest is probably to be avoided,whereas ISO resin is more shape stable and resilient for the (~20%) extra $.
Also,by the time you are using vinyl or epoxy,,you'd also need to consider vacuum technology to acheive the strength/weight factor to justify the materials.