Epoxy Alternatives/split from Hendo's build thread

[Parmenter]

The products I am using are Boatcraft Pacific Australian made Bote-Cote. The filler is Bote-Cote faring powder mixed with the bote-cote epoxy resin system. I have to use 80 grit sanding belts due to its concrete like strength.

Yep, thought it looked a bitch to sand

You may consider Qcells which are light and easy to sand and I have used them with great success for decades though they are getting pricier than they were but still cheaper than bote cote list for their powders
or I am looking into these Cenospheres - Fillers, Lightweight - Kirkside Products Perth WA from WA - want to be my guinea pig?
I imagine they would cost a fraction of what Bote coat and Qcell are charging for their powders.

 

[Nomad Willy]

I used vinyl paint called Bote Coat (not sure of the spelling) in the early 70s. Was a very good product but was very thin and didn't adhere to old paint.

Wonder if it's the same company.
The cans were mostly red.
They also made aircraft finishes that were lightweight.

 

[psneeld]

Not sure why but anything "spheres" are not recommended for use below the waterline by some of the epoxy suppliers I have dealt with.

However found this...so it's a use with caution maybe?

"However, glass bubbles produce a more waterproof filler mix and"​

​

http://www.boatpaint.co.uk/datasheets/sp/Filler Guide.pdf​

 

[Parmenter]

Not sure why but anything "spheres" are not recommended for use below the waterline by some of the epoxy suppliers I have dealt with.

Are they the same ones who try to sell you their expensive microballoons instead?
Microballoons are actually hollow phenolic resin spheres.

It makes no sense at all when you consider that (at least I always have) rolled in pure epoxy (to about 200mm above DWL) over finished product and then while tacky it gets several layers of waterproof epoxy highbuild/primer sprayed on it before the addition of any final antifoul or topcoats.

 

[psneeld]

Are they the same ones who try to sell you their expensive microballoons instead?
Microballoons are actually hollow phenolic resin spheres.

It makes no sense at all when you consider that (at least I always have) rolled in pure epoxy (to about 200mm above DWL) over finished product and then while tacky it gets several layers of waterproof epoxy highbuild/primer sprayed on it before the addition of any final antifoul or topcoats.

Just relaying what some "experts" in the field think...

Don Casey for Boat US writes...
"6. Now thicken some epoxy to a peanut-butter consistency with colloidal silica and fill the cavities with this filler, using a squeegee to compress and fair it. Silica-thickened epoxy is difficult to sand, so fair the repairs well. Never use microballons or any other hollow or absorbent (talc, for example) fairing compound to fill blisters."

So there are some pretty influential people in the field that think the amount of possible absorption degrades the possible repair or fairing underwater...again...I don't know the chemical reason behind it but there's other fairing compounds available...

 

[Parmenter]

Just relaying what some "experts" in the field think... Never use microballons or any other hollow or absorbent (talc, for example) fairing compound to fill blisters."

I wouldn't use it to fill blisters either.
But carving out gaping wounds in the hull structure and filling with low density filler is very different to a wafer thin screed of cosmetic filler on the outside of the structure.

 

[psneeld]

I wouldn't use it to fill blisters either.
But carving out gaping wounds in the hull structure and filling with low density filler is very different to a wafer thin screed of cosmetic filler on the outside of the structure.

I agree...but the concept that he states elsewhere and others suggest "less absorbent materials" are recommended over everything else for ANY application below the waterline.

 

[Scary]

Blister repair

Polyester resin and chop glass fiber or layers of mat disks whetted out with resin makes the best blister repair. Sands better , more flexibility as to working time and temp range. Why would repair a polyester laminate with a different resin? Would you weld steel with aluminum welding rod?

 

[Art]

I'm posting here so I get notice of others' posts. I've nothing to add, yet... Please carry on! I appreciate the info I'm reading!!

 

[Parmenter]

Why would repair a polyester laminate with a different resin? Would you weld steel with aluminum welding rod?

No because that obviously would not work
But epoxy is a far superior product to poly and if you are cutting out blisters from polyester failure, why would you want to put the same crap back in?

 

[Parmenter]

I agree...but the concept that he states elsewhere and others suggest "less absorbent materials" are recommended over everything else for ANY application below the waterline.

Well, all I can say is 20 plus years in the game and have worked on dozens of composite builds using that method under the waterline and I havent had a problem or heard of one yet.

 

[FF]

Why would repair a polyester laminate with a different resin?

Because secondary bonds with polly are very difficult to get strong , and polly shrinks over time , calling for yet more fairing., perhaps a year later.

Polly is great to new BUILD a GRP boat , after that epoxy is the glue of choice.

 

[psneeld]

Seems like manufacturers say they are OK (of course they want to sell them but after decades, failures would put an end to that practice I would think), end users say no (probably because of failures whether microballon related or not) and suppliers send cautions that ring of both.
So I'm not sure whether to use them or not.
Here's just a few of the yes/no support...
Yes
http://www.shop.aafibreglass.net/Phenelic-Microballoons-1Lt-9318098716903.htm
Phenelic Microcballoons are extremely tiny hollow phenolic resin bubbles. They are used as fairing fillers in boating projects (suitable for underwater applications) and lightweight fillers when casting etc.</SPAN>

http://www.altexcoatings.co.nz/vdb/document/1345
Microballoons
Premium ultra light weight filler for fairing, filling and filleting above and below water lue Powder improves sag resistance and application properties.

No
http://www.bertram31.com/proj/struts/struts.htm
CAUTION! Do not use fairing compounds that contain microballoons for underwater fairing! One excellent epoxy compound for underwater fairing use is the FASCO #26 FAS-FAIR. It is a pre-thickened compound with silicone as one of the thickeners, but must be made thixothropic by the addition of cabosil. FASCO makes several good general purpose epoxies that are mixed with a 1:1 ratio. Most fiberglass suppliers carry these products.

http://www.boatus.com/boattech/casey/blister-repair.asp
You also need a filler to thicken the epoxy into a putty. Select colloidal silica. Never use microballoons or any other hollow or absorbent (talc, for example) fairing compound to fill blisters.

 

[sunchaser]

I am looking into these Cenospheres - Fillers, Lightweight - Kirkside Products Perth WA from WA - want to be my guinea pig?

And to what advantage?

 

[Nomad Willy]

Tom I've always thought it's to decrease the density of some resins. It's extensively used in home built aircraft as it makes the resulting structure much lighter.

We choose mass in boatbuilding be it plastic, metal or wood. The scantlings are a big part of it but the density and strength of all the materials is also very important. That's why we seldom see a boat made out of the same species of wood. Oak frames, cedar planking ect.

Using something as heavy as plastic makes for a heavy boat (or AC)
and the microballons can reduce that weight significantly.

And if the boat isn't going to be abused just a good coat of paint is all that's needed. Repairs are a lot easier that way too. And w/o using expensive or exotic materials or methods the plywood boat will be stronger and lighter. But the easiest boat to repair is a planked wood boat. No glues or adhesives. One should be able to take one apart completely and reassemble. Requiring new caulking of course.

 

[Parmenter]

Yes - Yes - No

All sorts of views and opinion on the internet, rarely does any of it agree with others.

 

[Parmenter]

And to what advantage?

Save weight , save labour, save excessive sandpaper usage, save $$

Have you ever tried to epoxy resin and microfibre (glue powder)
Try longboarding concrete to find out

 

[Parmenter]

Why would repair a polyester laminate with a different resin?

I would do it because
A) epoxy is a far superior product
B) I have no poly but plenty of epoxy

Because secondary bonds with polly are very difficult to get strong

Only if you have poor prep

and polly shrinks over time , calling for yet more fairing., perhaps a year later.

Never seen a problem with epoxy/poly/fairing.
If its such a problem as you claim I wonder why the experts, when doing blister repairs on failed poly, use epoxy ?

 

[Parmenter]

Tom I've always thought it's to decrease the density of some resins. It's extensively used in home built aircraft as it makes the resulting structure much lighter.

Using something as heavy as plastic makes for a heavy boat (or AC)
and the microballons can reduce that weight significantly.

And if the boat isn't going to be abused just a good coat of paint is all that's needed. Repairs are a lot easier that way too.

Exactly

 

[kulas44]

I like epoxy and Cabosil, but micro balloons sand much easier. Epoxy and milled fiber is stronger than either. All that being said, I generally use sawdust, or if I need a really smooth surface I use sander dust. On occasion I have used plain white flour, non rising of course . I NEVER and will NEVER use polyester for any boat repair. Anything encased in epoxy will not absorb water.

 

[psneeld]

I like epoxy and Cabosil, but micro balloons sand much easier. Epoxy and milled fiber is stronger than either. All that being said, I generally use sawdust, or if I need a really smooth surface I use sander dust. On occasion I have used plain white flour, non rising of course . I NEVER and will NEVER use polyester for any boat repair. Anything encased in epoxy will not absorb water.

Really should read up why poly or vinylester is the better repair material for some repairs and yes, Epoxy does absorb water...some way more than others and some little, but still absorbs (read West System tests...and that's just one of many that confirm it).

 

[kulas44]

O lot of folks use poly and vinylesters, I don't. Epoxy is more expensive but is far superior to either of these in every way. it's a little more difficult to mix and takes a little practice to use correctly. there are a lot of different types of epoxy designed for different applications. A flood coat epoxy would not be good for laminating. A thin laminating epoxy will work as a filler when thickened with additives, but a thick epoxy will be stronger and require less filler. Polyester resin over plywood is a good example of why I dont use it. The layup has to be so heavy to keep from delaminating that you can actually use thinner ply. At minimum you need to use a 24 ounce fabmat layer, then a fill coat followed by a scrim cloth to make it smooth enough so you dont have to fair as much. Its a pretty heavy layup but it works. Its also heavy. Epoxy on the other hand over ply (3/4, say for a deck) would require 2 layers of 10 ounce cloth, thats it, with little fairing if you do a decent job. Much lighter, just as strong, no delamination. I buy Epoxy from U S Composites. Its much cheaper than any others and they have an excellent selection. Anything from a 1 to 1 general use epoxy to a 5 to1 super strong epoxy. I use a lot of the 635 thin in 3 to 1 for laminating and 1 to 1 thick for filling and gluing. They also sell "boatyard poly" and I sometimes use it for building fg items. And I have read everything I can get, and researched, epoxy/poly. Back in the day poly was what we got, all we had. I used a lot of it. Experience has shown me that epoxy is better.

 

[psneeld]

It's not better for large flat section repair because it has different properties and can create flex spots that will fail the surrounding polyester...been know to happen quite a bit.

EVERY major yard /glassman I know uses poly or vinylester repairs for large sections but will use epoxy for bonding, filling smaller to mid sized holes (thruhull size) or high structural repairs.

While epoxy is better "glue" it's not the best product for every job.

I too buy from US Compsites as I completely stripped my hull bottom and laminated a 6oz cloth/epoxy barrier under Interprotect 2000 last eyar. I also glassed all my decks after teak removal which if I wasn't buying bulk epoxy and were really just a top coat, I would have used vinylester.

 

[kulas44]

Agreed, sometimes we need to "build" a section then put it into the structure. We build it with polyester then tab it in with epoxy. Poly and vinyl are great for building boats, just not for repairing. I see you did not use vinylester to laminate your barrier layer. Why is that ?

 

[psneeld]

Could have but didn't...50/50 shot and after talking with Interlux they convinced me to go all epoxy for a real thick barrier coating...either system I'm sure works fine.

Poly and Vinyl are used by some big yards I have heard from and the guys I work with for hull buildups after large sections have been removed for damage etc...and they are just faired in, not tabbed with epoxy.

 

[Parmenter]

Epoxy on the other hand over ply (3/4, say for a deck) would require 2 layers of 10 ounce cloth, thats it, with little fairing if you do a decent job.

Multhullers would generally use 3/8th ply and a single layer of 8oz.
I have even been on 30 ft cruiser/racers that have only used 1/4 ply on decks and hulls, but I felt the need to walk dainty on these ones.

You can build amazingly light and stiff structures if you get your framing right

 

[Brooksie]

I made a repair to the bottom of my lobsterboat almost 3 decades ago using 3 gallons of polyester resin & a sack of glass microballons. It involved an area near the stern 4' X 5' and 2" deep at its center (a defect in the initial molding of the hull). I remember screeding it off like concrete while upside down in the snow. Epoxy was completely unknown to me.
That repair is still there and has never chipped or loosened in all that time and quite a pounding over the years.

 

[kulas44]

Epoxy would not have been the thing to use "in the snow". That is one reason most folks like polyester resin, it will go off and set up, and its easy to use. that and CSM makes polyresin a no brainer.