Rob590

Hi all...

I'm new here on RCUniverse, but not new to the hobby...

I have a question regarding vinylester resins... I know that they fall between polyester and epoxy resins...

For now I have used only epoxy resin and never had trouble with it... Good thing was that my father always kept 50+ kg of epoxy for his sailplane... As his sailplane project goes to an end, so our epoxy stock goes out... We used Sika Biresin SR120 resin and Sika Biresin SH120-3 hardener...

Now Igot access to cheap (read free) vinylester resins mixed per my needs by my friend who works at the resin factory...

I would use vinylester resin only for covering my models with lightweight glass cloth and Iwould still use fast setting epoxys for construction...

Is vinylester suitable for such application?

Cheers,
Robert

wyowindworks

Vinylester should work well for that. The major hobbiest drawback to vinylester resin is it's very short shelf-life. Once the container is opened it can go bad in as little as 3 months. There can also be some curing issues in humid conditions. I would consider using vinylesters for many applications but the short shelf-life makes it too impractical unless you're using it quickly. It will also attack polystyrene based foams so you have to use caution with foam core wings.

Rob590

Thanks for fast reply...

Short shelf-life won't be a issue because I can get resin in small pots and I can get resin tailored per my instructions...

Avaiojet

Vinylester resin.

I don't even like the sound of it.

I've used Polyester resin for many years.

I wouldn't change my winning game.

lfinney

My Feedback: (44)

vinylester resin is used by gm for the body panels on coorvettes and the likes, its a better resin than polyester, ,less shrinkage less brittle, etc. most new surfboards are vinylester if they arent using epoxy

John Sohm

My Feedback: (9)

If you check it out, you'll find that vinylester resin is superior to polyester. Check the following site for info: http://www.uscomposites.com/polyesters.html and then look at the description for the 700 Vinylester resin. I wouldn't mind trying it out myself sometime in the future. I've worked with both polyester and epoxy. Polyester gives you a harder finish but the smell is a killer in a confined spot. The epoxy I use is almost odorless and almost water thin too.

wyowindworks

Dang.....I just realized that I have now posted twice in this thread on the same topic. I'll leave it up since there is a bit of new info.

The biggest downside to vinyl ester resin is its very short shelf life. Most manufacturers recommend using it within 3 month of it's delivery date. This works great for large shops that use lots of resin, but most hobbyists just aren't able to use it fast enough. You can also get vinyl ester in a unpromoted state. This will extend the shelf life. Before using, the promoter must be added to the resin. Then the hardener is added to the resin to make it cure. If the vinyl ester is unpromoted it will never cure no matter how much MEKP is added. WARNING: If you mix MEKP and the promoter directly it will explode. It's typically safest to acquire the vinyl ester that is pre-promoted and deal with the low shelf life.


Adam

Louis9624

One thing to consider is vinylester resin has viscosity much thinner that epoxy. This may not be an issue, buit if you are covering balsa wood, I think it will be absorbed by the wood, making for a heavier part. This may or may not be bad, (more strength for the wood). Vinylester is usually a little higher strength, but don't be fooled, vinylester is a little more brittle.

wyowindworks

I always seal the balsa regardless of the resin. There are many high quality epoxy resins that have near the same viscosity as vinyl ester.

Epoxy typically has a higher tensile, compression, and interlaminar strength than vinyl ester.

John Sohm

My Feedback: (9)

Good Lord, you guys are talking about brittleness and too thin a viscosity like you're designing the next generation of space shuttle. Everyone is going to have their preference as to what resin to use. Polyester or vinylester will give you a harder surface than the typical epoxy resin. But think about this, a lot of other guys are basically using a polyurethane paint to bond a layer of glass to the balsa. The glass cloth or whatever you decide to use to bond to the balsa is basically there to prevent the balsa from splitting or checking. It stabilizes the surface quality of the balsa. That's it in a nutshell. Whether you use polyester, vinylester or epoxy is your choice. I personally use epoxy since the smell of curing polyester is too strong and reminds me of an autobody shop. That's not to say that the vapors are more harmful than the epoxy. Epoxy vapors are not healthy for you either. You will never see me advocate heating epoxy in a microwave for instance to thin it out. Use the proper type epoxy for the job at hand. If the guy who started this thread can get vinylester at a reasonable cost to complete his models, more power to him. It will work fine. Just don't use it or polyester resin over bare EPS foam or you will end up with a big glob of goo. Remember, to thin polyester resin, you use styrene monomer and since EPS is Expanded PolyStyrene... well you get the picture.

Well anyway, I'll get off my high horse now and I hope I didn't offend any one.

Bundubasher

Hahaha, yes. Things that is important for me: is it lighter, stronger and/or cheaper?If it is harder (I use cotton flocs if need be) it is ok.

Butif I have torun the risk of explosions andtoasting my family jewels when mixingMEKP and "additive b"together,it is not practical for me.

Avaiojet

I'm too old and too set in my ways to change my building habbits. Although I should probably learn a bit more about various offerings.

My new buddy. A fresh can of Polyester resin.

darren763

My Feedback: (117)

They do make Styro-safe Polyester resin, here is a link of a supplier. Great way to make one off's or plugs from foam. And yes vinylester smells the same as polyester resin to me. so use in well vented area.

Darren

http://www.expresscomposites.com/resins.html

Rob590

hey all

I thought that this thread is dead, but wow, so many answers. Thanks for that.

Yes, I can get vinylester for free, but I tried all systems and I'm sticking with epoxy. My epoxy supplier buys high quantities (1,5 tones) of high quality epoxy resin (Sika) and I get it from him at really low price.
 
And epoxy is really nice to my foam based models (not that I attempted to use polyester on EPS, after all, I am chemical engineer )

Louis9624

Good Lord, you guys are talking about brittleness and too thin a viscosity like you're designing the next generation of space shuttle.  Lol Lol Lol -this one will be good to bring up during dinner-Lol Lol Lol

RAPPTOR

My Feedback: (41)

}vinylester resins }Better than sex!! I tried them all. Wear a mask and use it..kEEP IT IN THE FRIEG.AND LAST 2 YEARS..

Centralrchobbies

My Feedback: (7)

I use vinylester resin on all my fiberglass boat layups would never use anything else good stuff stiff and strong.

carmbrister

Hello , I'm actually interested in polystyrene foam dissolution in vinyl ester resin. Do you know any specifics about this reaction?

countilaw

I guess we old builders have two questions, Is it cheaper and easier to sand? I'm too old to get too bogged down in viscosity or flexibility or tensile strength. I guess I will just stay with my tried and true methods and build models.

Frank

RAPPTOR

My Feedback: (41)

price good .. sands easy. just has faster setup . 90 plus degrees is like 30 minutes .
I have gone down to .5 percent -mek . get a little more time .