Epoxy verses Vinylester

Epoxy verses Vinylester

I have peeled the old polyester gel coat off my boat. It is now very dry about 2 years out of the water. Will start to apply the new barrier coat. First with a penetrating epoxy then about six coats of epoxy, done during the chemical bond sequence. Followed by 4 coats of epoxy high build primer then followed by the bottom paint of my choice prior splash.

Lately I have been hearing other guys saying that the epoxy will blister, this I could understand if the laminate I was coating was still wet. Also others have been saying the Vinylester sticks better and would be a better barrier than epoxy. This flies in the face of what I know. All of your comments would be welcome.

Jack

 

Hi Jack!

This is an on-going question in these columns and my observation has been that the order is epoxy, viny then polyester. Same order as the price, coincidentally!

I don’t profess to be an expert so I can’t answer you direct; but I’d just like to point out a nifty feature of this forum. Once you publish a question, similar questions are automatically generated at the bottom of the existing page. Just scroll to the bottom of this page and you will see a section entitled “Similar Threads” This is always a good place to start though I’m sure the pundits will be in soon with their invaluable views. Good luck mate!

 

Stop paying attention to those that have been saying epoxy doesn't stick as well as vinylester and that it will blister. They're frankly talking out their butts and haven't a clue.

Epoxy is better in all regards (in every way we can measure things) then vinylester and far better the polyester. Don't bother with a penetrating epoxy coating, just apply sufficient coats of unthinkened epoxy to form your barrier, then prep for paint. Use one of the particularly low viscosity versions, like Raka, Epifanes, System Three Silvertip or West System 209

 

Using incompatible material is the only time Ive seen epoxy blister. Like using any urethane based product with an epoxy based product. Guaranteed blister. Or laying the part up very resin rich.

Also, epoxy willl stick to vinyl ester better than vinyl ester will stick to itself. But not the oposite. You also have a very short time period for secondary bonding with VE.

PAR: You ever use Adtechs 820 resin? Its in the 350cps range (medium hardner), and is solvent free.

 

No I've not used the resin you mentioned JRL. Who's your supplier?

Epoxy can blister or otherwise fail, but I was assuming that poor prep, incompatible materials and improper mixtures could be eliminated from the focus of the discussion.

JRL, drop me an email or IM and let me get a handle on the Adtechs 820 resin.

 

I buy it through GE Polymershapes. We use it for our resin infusion applications.

CASS Polymers is the parent company for Adtech Plastics. They also make really cool epoxy tooling dough (for molds that must keep exact demensions).

If you need slightly higher CPS values the fast and slow hardners put it in the 400/450 range. Working time is fairly long also.

 

Why not use Penetraing Epoxy

Thank you all for the input. Question PAR what is the down side to using penetrating epoxy prior. Jack

 

why not use interlux interprotect 2000, its a epoxy with suspended micro plates, which act like shingles on a roof , once the hull is striped and dry roll on a coat of the 2000 , then with there filler fill in any holes and sand smooth then follow with another 5 coats, the window between coats is 2 weeks, then bottom paint, I have done many hulls this way and none have come back ,

 

Penetrating epoxy offers no advantages, on your polyester hull, Stevens47.

 

Hi all,
Listen to Par, low visconsity epoxy like Mas,www.aeromarineproducts.com or fiberglass coatings inc brand are all superior for restoration or rebuild type work. And ditto on the penetrating resin question.

 

I have had very good results with the West System!!!

 

There is another reason for the blistering UNDER epoxy and mostly applies to poorly laminated boats like the Stevens 47. It is the MAT layer of glass they used to "pick up" the gelocoat in the mold. For some reason nearly every 47 and the Pilothouse 52's have the same issues, terrible laminations resulting in the need to peel that layer of glass to properly perform the blister removal.
You will most certainly experience more blisters down the road regardless of the materials you use. It's the migration to the WSMs (water soluable materials) in the polyester resins used. You may think your boat is dry, but the condition still exists.
IF you use epoxy, you should at least laminate an entire skin over the area, using 4-6 oz CLOTH, NOT MAT!!! Then you should be fine using epoxy, which btw is NOT the end all answer to boat repairs. Thermal expansion rates do apply to the 47 most due to its flimsy construction, lack of structure etc. If the repair resin expands at different rates , trouble is on the horizon.
Vinylester resin IS the correct choice for this type of repair, rates are similar, same styrenated family and a very high end resin( I am BTW an epoxy builder by choice and HATE styrenated resins.) yielding a similar movement of cloth(such as it is in those boats) and resin. Again the proper way to eliminate blisters in a boat with such low quality construction is to peel the first layer of glass, then either chop a layer of mat using vinnies or hand lay mat using the vinylester resin.
Blisters in this type of boat most definately come from the interface of the first layer of mat and the following laminates. The conditions in the shop at the time of lamination, quality of resins, cleanliness of workers and DIRT! If the gel and first mat have been allowed to fully cure, there is an instant tension in that layer as the following laminates are applied, that pressure is a breeding ground for blisters, drawing the water through ANY barrier.
Before you apply porduct, have that boat checked out by an expert at peeling................DO NOT just apply epoxy, it MAY just create a barrier PROTECTING the blister condition and most likely crack due to expansion. You sure dont want to have to peel deeper in the future, after spending the $$$$$$$$ to capture what is still there. Just the thought of all that sanding over and over again to gain mil thickness with epoxy....................

I dare say, I dont like using my "butt" to speak, so I guess one should remove ones ear from others arses.............

 

Are we talking about the same boat

Tynaje,

Thanks for the input. Are we talking about the same boat. The boat I am talking about is built by Queen Long who build the Hylas line of boats. The boat is constructed with longitudinal stringers and transverse stringers and has very heavy laminate. I have peeled not sanded the gel coat off, there was minimal blistering at the time probably about 30-50 quater sised which are apparent after the peel. I have done some hull repair and rebuild using epoxy and vectorply quad laminate, so trying to stick vynil over would be hard. Can any of you guys recommend the correct thickness (MICRONS) of the epoxy, I am thinking of using Jeffco 1314 with w/3103 hardener the physical properties are Viscosity 350 shore d hardness 83 elongation 7.5 tensile strength 27,00 psi flexural strength 30,000 psi. If it is nessary I will laminate biax over?

Jack

 

USED Epoxy on many a boat. It will only delaminate if surface that is to adhere on is not properly cleaned, which usually means sanding. But leave it a little rough before applying, dont over sand. Also Sand in between coats unless you recoat at tacky stage.

The only problem with epoxy is UV. Remember to protect it by painting

Dont buy super cheap Epoxy. West, Mas and others are great. Also watch moisture content of old epoxy. I learn hard way old epoxy was left open and we used it. It never cured properly.

 

Vinylester vs. epoxy

There is a new vinylester by AOC which has a tensile strength of over 13,000 psi, which makes it stronger than epoxies usually used in boat building. Many people are using vinylester for blister repair, though I would hesitate to use in when laminating to wood.