epoxy board cure time

I know this topic has been kicked around, but always having to do with questions regarding what type of epoxy, post-curing rates, and glassing.  I just picked up an epoxy board that was glassed a few days ago, sanded finish.  How long should I wait with the board in a garage at 70+ degrees before I should ride it?  Any data on this?  Thanks for any info.

Depends on the brand of epoxy.  Fiberglass Hawaii epoxy, full cure five days.  That would be from the day of application. 

Bottom - First day,

Deck - Second day

Deck Hot Coat - Third day

Bottom Hot Coat - Fourth Day

Fins - Fifth day

Sanding - Sixth Day

You get it - Seventh Day

So by the time you get the board, the deck and bottom laminations are fully cured.  By the time you get it home and to the beach, it is mostly cured, so you are just worring about the hot coat and fins for full cure. If insert fins, then the order changes and don’t worry about the fins at all.   And that is if the shop delivered it to you promptly.

 

Enjoy your new board.

So it sounds as though if I wait another week before riding it, I should be OK, depending on epoxy brand.  

There are waves on Tuesday.  Go get it wet!

when you look at the FGH aluzine specs it claims full cure at 75 degrees is 14 days.

It also claims no “hot coat” sooner than 8 hours and no later than 24 hours unless rough sanded prior to “hot coat”

 Day 1(8 hour day)- I would do a top and bottom with a filler coat of resin when just past tacky on lam(approx 30 mins after initial lam)Repeat on deck when lap in sandable. Preglass fin boxes of course.

Day 2- sand and final coat with epoxy top and bottom

day 3- sand finish you are done surf if you want,/option 2 -Spray UV urethane if applicable. 

day 4-1000 grit quick buff if UV sprayed, surf if it is up.

The devil is in the details.

Unlike PE resin, epoxy is about 70% cured immediately when initial hardening takes place. The reason you have to wait so long(ie2- 3 hours with FGH, lam and filler coat) is to get it to be able to sand for whatever the next step is. If you have a finished epoxy surfboard in your paws there is no need to wait for anything. You have a stronger product than PE resin and fully cured times and cured enough to surf an epoxy board are two differnt things. 

Your issue now is if the foam density and layup schedule was sufficient, not full curing time of epoxy. I have never waited or kept a finished epoxy board in the rack for curing like you routinely see with PE builds. I have used increased ambient temps to expedite time between steps.

If waiting gives you piece of mind then please wait. But everysurfer summed it up well noting that most manufacturer would never get you a board in less than 10 days. I think waiting for optimal cure of epoxy boards is a non issue for home builders and customer situations. with FGH fast cure and RR fast cure resins.

lessee, middle of July in Florida.  For us, put it in the attic, 3 days later it’s golden.

I think it is different for different Fiberglass Hawaii speeds.  I got five days off a bottle of fast cure hardener.

Another thing, Fiberglass Hawaii has two epoxys  

  • Regular and three minute epoxy.

and three hardeners.

  • Slow, for regular laminating. 
  • Fast, for ten minute pot life.  Mix one batch, and go stringer to rail.  Mix second batch to go stringer to other rail.
  • Fast and thick. To thick to laminate with, but is thickened to do a thicker hot coat.

See for yourself

 

http://www.fiberglasshawaii.com/resins/resins-epoxy/resins-epoxy3.html

 

All the things you just said have me scratching my head.

My 20+ year experience with the product tells me different.

the type of epoxy resins they have is an aluzine type. 

3 minute epoxy to do what with beside small repairs?? 

Cure time occurs after the resin initially sets, so the speed of hardener is irrelevant.

Slow hardener for lamination is unecessary and for green room epoxy NOT recommended per spec sheet.

The slow hardener comes out for the 12 foot plus boards getting a veneer or planks or cork laminated by vacuum bag with 1 man construction and no helpers. Helpers available use fast hardener.

Glassing with fast should not be a problem under 80 degrees F.

 

My whole point is, if your epoxy is hard enough to sand, the board is ready to surf. You are continuing the epoxy urban legends from pre clark foam closure. 

You should try glassing the whole board with fast hardener and with one batch. A 6 foot board might take 5 minutes and a 10 foot board maybe 10 minutes.

why so timid? I think mixing multiple  batches of resin just allows you more oppotunities to make a mistake.

Maybe it is just me, but your routine seems slow and inefficient and in my opinion not the standard

But if it works for you great.  

 

 

 

 

I just checked my bottle.  I’ve been doing some laminating between swaylocks posts today.

My bottle of Fast says pot life of 10 minutes.  For me, that’s just too quick to laminate, especially a deck with two layers. I like to play with it a little too much, I’m sure.  But I like the slow, because you can really pull off the extra epoxy.

3 minute epoxy is for setting fin plugs.  Almost no exotherm, and with three minute pot life, they are set in place in about ten minutes.  Don’t use it for repairs, because although it sets hard in ten minute, it stays like rubber for about another 12 hours, so you can’t sand it until the next day.

Another thing about FH epoxy.  The bottles have wrong directions on them.  Stuff like clean up tools with acetone.  THe guys in the Ventura store know about the labels, but I guess the Main Office doesn’t. 

When I have questions, I ask Wade and Steve in the Ventura store.  Great guys that know their stuff.

My 5 gallon containers and 55 gal drums have no directions on them, just content indentification. 10 minutes seems pretty quick for pot life. I guess I get it on the board quickly and it doesn't kick like a full bucket.would..Using fast cure I have big board size veneer/plank and cork vac pulls is at least 15-20 minutes wet out.tape down. pull ply,release film and throw it in the bag with full vacuum. ................never had a problem.  I wonder what the listed pot lif for slow cure is??

I remember back in the day keeping boards in the vacuum bag for 12 hours +, Now with fast cure and a hot house it is 90 minutes and ready to do the other side. Times have changed, resin formulas are new and improved. Good times indeed.

Guys who sell it and guys who use it are two different animals. Just with the info on the spec sheets regarding cure times and when to use a filler coat tells me I technically have been doing it wrong all these years with amazing success..

That's why a little knowledge shared can be harmful to the inexperienced. I forget about the dozens or hundreds of variables that go into an off label use of a product. These variables and the corrections that take place to make something work are hard to describe and share due to the vast volume of knowledge and experience that goes into it. Good judgement comes from experience and experience comes from bad judgement.

If the directions are working for you all, please keep it up. I honestly never recall reading the directions except for 2 to 1 mixing ratio by volume and fast or slow cure.

rock on dudes

24 hours at 100F min. is what the chem engineers I know say for any type of epoxy, and they’re the guys doing aircraft skins.  At 75F, it’ll take about  3 weeks to fully harden but it won’t acheive the same strength as a heated post cure.  Post cure is done after hotcoat, and ideally with some hole into the core open (leash plug, vent, etc).    Don’t confuse the timing of epoxy to reach a sandable surface to be the same as cure time.   The terms “fully hardened” or “cure time” for any thermo-set resin means when the material reaches maximum strength, and this is alway defined as a specific time and temperature.    Almost all epoxies are usually spec’d at 275F for 2 hours, but this is of course not viable for EPS.   So, the various surfboard epoxy brands probably never reach their full strength potential, but at 100F / 24 hrs it’s maximized in consideration of the EPS core.

Hey Pete,

 Can you answer the question to the original post? Would you surf his board or wait? No production shop to my knowledge post heat cures epoxy surfboards in Hawaii.

I don't like the word "Hotcoat" when discussing epoxy. Are you saying you post cure after the first filler coat of epoxy for 24hours, then sand and final coat with epoxy for polished or sanded finish????

I still believe full cure of epoxy is not necessary for use. That's the great thing about epoxy resins in my opinion compared to PE resin builds.

Love your Vents Pete. Have to order more soon.

Shame on them. 

Greenroom resin sands great, while skin still flexes. After post cure, skin is hard as a rock.

When I build 14 footers I can’t post cure. Skin flexes. Skin doesn’t get tough for a week or two. When I build boards under 8 feet I post cure in my laundry room with the door shut and ceramic heater running for 24 hours. Room stays 100 degrees.

The Greenroom factory in Wilmington post cures all their boards in a closet in the back room of the factory. So easy to do and the boards end up tougher for life.

Just wanted to add a little something.  Both Wade and Steve are professional glassers.  Steve used to do glossing for I think he said Yater, but I could be wrong.  I’ve seen Wade’s boards, and his shaping and glassing are the best of the best.

The both work in the Ventura store.

Dwight, So when do you post cure??? when the board is totally finished or when Pete suggests??

Regarding green room epoxy, I am not an expert with this epoxy, having only done 2 sup's with this system. I used fast set and went runnig to the website to get the Spec sheet sheet.after the first side lam.

spec sheet as follows:

PHYSICAL PROPERTIES with Fast Hardener
Density (mixed) 1.11 g/ml
Form and Color Clear Liquid
Viscosity (mixed) 700-800 cPs@77ºF
Mix Ratio by volume 100 parts A/50 parts B
Mix Ratio by weight 100 parts A/44 parts B
Pot Life (100 gm) 15-25 Minutes @ 77ºF
Peak Exotherm 160ºC (100 gram mass)
Thin Film Set Time 2.5 Hours @ 77ºF
Full Cure Time 72 Hours @ 77ºF or 8
hours @ room temperature plus 2 hours at 212ºF

Not sure how you tested and came up with the post cure procedure to go with 100 degrees for 24 hours. The website spec sheet says room temp cure is just fine in 72 hours.

My knee jerk reaction was to get the freshly laminated board to my hot house to speed the cure. This was not practicle due to board size and contamination ofthe wet lam.

I am kind of quessing you have never used FGH aluzine, so you probably can't understand the night and day differences in the products. I will be sanding the green room board this week and see how things go.. If post cure rooms are needed to make it work, It just will not be possible to have a 16' x 10'  area to post cure like you suggest.

Still figuring out the green room resin. It has a lot of nice proerties.

I have no dog in this hunt with epoxy. Just hundreds of gallons of experience with FGH/RR products. Been through all the "new and improved formulas" of these products. Just as of now, the hype has not lived up to the reality of GR and I don't share your joy you have of the product. I will give a detailed head to head comparison when I finish the 15 gallons I have.

aloha and thanks for the tips on your post cure formula. I will try it with some shorter boards.

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Guys who sell it and guys who use it are two different animals.

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Just wanted to add a little something.  Both Wade and Steve are professional glassers.  Steve used to do glossing for I think he said Yater, but I could be wrong.  I've seen Wade's boards, and his shaping and glassing are the best of the best.

The both work in the Ventura store.

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I wasn't slamming your buddies with my comment. If they are master epoxy glassers then cherish and use the advice they give. They can probably attest to all the nice aspects of aluzine when glassing surfboards. Maybe your buddies can encourage you to use fast set hardener and do it all in one shot. See what they say next time you are in ventura. I learn something new everytime I visit my FGH store.I am quite sure though I know more about the use of aluzine than every employee there combined.. You know, the small things. That certain viscosity, the special smell it gives off just minutes before critical exotherm. How long to keep it in the microwave to thin it out. Knowing when you can just walk away and no longer baby sit your board.

Will the honeymoon every stop with aluzine???

The Greenroom factory is 15 miles from my house. They helped me a lot. Dr Rob has helped me too. 

I bake after hot coat. I sand after baking.

Dr Rob can give us the best explaination for baking. I’m not sure I’ve got the story completely accurate, but it does something like permanently rasing the temp Epoxy begins to soften at in the hot sun, for the life of the board. I think it makes it stronger for the life of the board. If you Google the subject you’ll find lots of techy stuff on how epoxy is better for life when baked.

The smell just before I say “Oh Nooooo” unless it is just the left over in the bucket going critical.  Same smell as when you over sand and over heat.

For the microwaving, I learned by wasting a bit of epoxy, that you can’t microwave the epoxy in the jug, and then pour it out.  Last winter I was heating it to get it to pour out of the jug easier, but when I got to the last cupfull or so, it was all lumpy, and chunky.  Only microwave what you are using.

Hey Charlie, I find that if I wait several days it sands much easier, so even if I lam a board quickly, I try to wait to sand the filler coat and finish it. Otherwise I get a lot of gumming on the sandpaper. When I wait it sands with a lot less of that gumming up.

But it’s several degrees cooler at my house than in Ewa.

By the way, Keith says we’re having a get together this Saturday at your house. Bernie and I will be there. What kind of beer do you like?

Can anybody tell why FGH recommends "no sooner than 8 hours"  on the fill coat? 

I might to rethink my use of the "Lam-Fill-No Flip" method.  So far, it has worked perfectly to eliminate delam issues I have experienced after cold temperature blush.  I'm open to suggestions anyway.