I was looking at the prices for resin research epoxy and due to their high prices i began wondering. would it be possible to lay a base coat/ first layer of glass of RR epoxy onto EPS and then follow it up with resin to finish up the glassing? or would that affect their bonding and strength caracteristics? also, would it even save me money? just a thought… -cam
By “resin” I am assuming you mean polyester resin? If that’s what you mean, no. You don’t want to do that. Any polyester that makes its way through the lam will dissolve the EPS. Some people have done poly gloss coats over the epoxy hotcoat, but with mixed results.
Resin Research is worth the money, IMHO. Money well spent.
Hey nova…
The idea you present is one thats long been utilised. The earliest use of EPS required sealing of the foam before lamination with polyester.
This was, and can, be done with spackle and housepaint, or micro-ballons in epoxy. Somewhere in the archives you will find a thread about the $5 blank…
I’ve seen EPS racing paddleboards requiring thorough and laborious squeegeeing over with araldite mixed with talcum powder…Certainly not new and not sophisticated. Bill Thrailkill recalls having seen this in the Hobie factory in the late 50’s (Bill?)
I can hear GL saying “hear hear” as I say:- Epoxy used well uses less…
Josh
Don’t know about RR epoxy but Fiberglass Hawaii epoxy says you can do it on the can.
I’ve done it with the sand/ and gloss coats with good results, but with one problem.
On light impact, the resin will chip off. If you did a lam coat, I think it would work.
I’ve been wondering about the compsand boards. If you use epoxy to skin the EPS,
then used resin for the glassing, it would have a better finish.
On the downside of resin glassing, it dings easier and smells worse.
On the upside of epoxy, since you can clean your tools and hands with
white vinegar instead of acetone at $15.00 a gallon, the total cost becomes closer.
Epoxy $ + white vinegar $ is close to Resin $ + Acetone $.
But if time is a factor, sun cure resin sure lets you do a lot of work in just a little time.
Decisions, Decisions, Decisions!
someone made an allusion recently to the fact that it’s the MEKP in the PE resin that melts the EPS…using UV cure is a workaround that permits you to use PE on EPS.
I don’t know if this is true…just floating it out there.
I have only glassed with epoxy so far but this is what I have gathered…
When laminating with Epoxy you want to do all of the steps right after each other, you dont want to allow the epoxy to fully cure in between lam/sand/finish(hotcoat?). This way you can get a chemical bond between the different stages. I dont know if poly works the same way. If you do poly on top of epoxy you will rely on a mechanical bond, you must rough up the lam with low grit sandpaper to give the poly something to grab on to.
Epoxy is stronger and more flexible (ligther too) than poly, it is more likely to dent under impact than to crack under impact like poly. This could be considered one of the advantages of finishing with poly, the hotcoat might crack if you get a ding, but the epoxy is less likely to, easy to spot easy to fix. On the contrary, I know that a very reputable company that does epoxy boards using RR, they use a stiffer version in their lam and then finish with a slightly more flexible epoxy. I have a board glassed by them and it is rock solid and light.
That doesn’t sound right to my, EPS is polystyrene, I always thought that it was the styrene in Polyester resin that was at least one of the solvents that disolved it.
There are a lot of variables being addressed here that affect what the ultimate outcome may be.
For the most part, epoxy resins are not compatible with polyester resin. However some types of epoxy resins such as Fiberglass Hawaii’s aluzine (epoxy) states that it will accept PE resin over it. The practice of sanding epoxy fill (aka hotcoats) with coarse sandpaper (50-80 grit) thereby creating substantial ‘tooth’ for a mechanical bond has been regular practice for decades.
Chipping off of the finish coat of PE is common when that coat is layed on heavilly for polishers to easily polish out the board w/o burning thru to cloth or pinlines. Thinner glosses do not seem to have this chipping problem.
I used both FH and RR epoxy over may years for different purposes. This included sanding RR hotcoats with coarse sandpaper and doing reinforcing of fin boxes, footstrap inserts, and deck patches on sailboards and surfboards w/o significant problems. Although a chemical bond was not possible, the mechanical bonds held fine.
The choice of board manufacturers to use two different epoxy formulas is a matter of personal preference. Some choose to use a stiffer higher modulus for the hotcoats and a more flexible one for the laminates, citing that the stiffer outer coat prevents dings better while the more flexible laminates deliver good flex characteristics in conjunction with the ability of EPS beads to absorb and recover from compression under typical load bearing situations.
A stiffer resin may be preferred by some manufacturers using fixed cell foams that are structurally prone to the cell walls crushing. This would be more commonly found in PU blanks, although some PU manufacturers have recently developed foam formulas that are more resistant to the age old crushing and eventual delamination scenario. Ice nine is one of the companies that has been able to achieve this while working in conjunction with Harold Walker (formerly of Walker Foam).
A few other foamers are claiming to have developed a similar smaller celled foam that still nets a less absorbent, lightweight surfboard blank, but I cannot attest to this claim as I have yet to shape any others than from Ice Nine, who is my primary regular supplier of PU blanks. I have been conacted by Surfblanks America, and they have invited me to shape what they state is a ‘finer celled’ formulation that they recently developed.
Whether you choose to glass wth PE or epoxy, if you are REALLY serous about the result you get or the product you provide for your customers, it pays to take a study of the Techincal Data Sheets of each product you intend on using. TDS sheets will disclose important information such as Tensille & Flexural strength ratings, Barcol hardness, and compression ratngs for the material before being applied with your choice of reinforcement(s) (cloth, veneers, fillers, etc.).
Careful choices in matching up the proper reinforcements is another important consideration when creating your product. If one makes a study of fiberglass reinforcements commonly used in modern surfboard production, you will find a variety of finishes on the fiberglass that are specifically for epoxy resins versus PE formulations, and vice versa.
The bottom line is, there is banging out a cheap surfboard, then there is building creme de la creme equipment second to none…
p.s. reader beware, not spellchecked!
That was always my assumption too Woody. I know that quite a few solvents will eat right through eps. I have tried some uncatalised resin on eps, it does melt it but not as quickly as I’d remembererd other stuff doing.
I also tested some catalised resin over eps with a coat of pva, when I was considering messing about with cheap alternatives to compsands (can’t remember what happened, might even have lost the test piece before I could ascertain results; man have you seen my garage?) Oh, there it is!
…hello,
obviously affect the strength and mechanical charact
why do that?
the cost?
if you re cheap you can t obtain a good board
a PS/epoxy is a “package” a whole to perform at it best
MEKP? I don’t think so…it is my understanding that polyester resins have up to 50% styrene in them and this is what allows the molecules to link together creating their structure. I can go pour some styrene of some scrap EPS I have and I’m willing to bet it will dissolve the EPS. In fact with enough immersion of styrene in a regular PU blank, it will probably dissolve it, as well as a cane MDI blank. Of course acetone just totally melts EPS.
Styrene is what give PE resin that characteristic smell aka stink.
What you are really looking for is a barrier coat to allow glassing an EPS blank with PE resin. I don’t know why you would go that route other than to save a few bucks…and I emphsize the word “few” in my statement.
**If you want to reinvent the wheel, you are probably better off coming up with a super cheapie version of a comp sand using some kind of adhesive for veneer to the EPS then just seal the veneer with multiple layers of inexpensive coating or UV PE resin. **
This thread makes me think of what Jack Nicholson said when leaving his shrink and looking at everyone in his doctor’s lobby in this movie:
"Has it ever ocurred to yuo folks that this might just be as good as it gets?
"MEKP? I don’t think so…it is my understanding that polyester resins have up to 50% styrene in them "
Give that man a cigar, he’s absolutely correct. Styrene monomer is your thinner of choice for polyester resin, plus it’s used as a solvent for the wax in sanding resin . Methyl Ethyl Ketone Peroxide really isn’t that likely to eat foam or styrenes.
Now, if you want to dissolve polystyrene foam…or make it into a Really Bad Tasting version of Marshmallow Fluff, styrene monomer is also the weapon of choice. Like dissolves like, one of the few things I definitely recall from Chem 101. (maybe I shouldn’t have sampled some of that stuff I was making…)
And a leetle bitty pinhole in an epoxy lamination with polyester resin over it will let in enough styrene to compromise the underlying foam. I’ll bet you can guess just how I found that out too…
hope that’s of use
doc…