Polyester resin help

General Discussion
1

Im pretty new to all of this. Im only 20 but i feel like Ive got the basics down. I have recently made 3 boards using eps and epoxy. For my next board i would like to do a resin tint and cut laps. From what i have read polyurethane blanks and polyester resin will give a much better result. So my question is, will using polyester be harder to work with? Should i start with UV cure? Any information and suggestions as to where i should start would be great.

 

Here are the first three. let me know what you guys think.

[img_assist|nid=1058150|title=5' 3"|desc=|link=none|align=left|width=640|height=480][img_assist|nid=1058151|title=5' 10"|desc=|link=none|align=left|width=640|height=480][img_assist|nid=1058149|title=6' 2"|desc=|link=none|align=left|width=250|height=640]

2

Timing is everything. UV takes some of the pressure off. You can lightly catalyze with MEKP in UV resin if you’re doing opaque. Have a friend around to help. Boards look good. I like the first one best.

3

Thanks for the input nj. Any brands recommended? And it looks like the UV can be used for laminating, hotcoat, and gloss coat with the addition of surfacing wax. Is this correct? And what is the purpose for using catalyst with opaque colors? Lack of sun penetration?

4

…hello, seems that you have potential.

In my opinion a tint lam is a waste of time; is the most difficult type of coloring to achieve right results and then after all that work, when you ding the board is not possible to have a good cosmetic repair on those.

Better than a tint is to do a pigmented lamination; will be opaque and will be better in case of future repairs.

You do this the same way than for tints.

The UV cat works with some pigmented tints without put MEKP, but is preferable to put at 2,5%.

and if you are fast and are using too dark colors you would use at 3-4%

 

-yes, is correct.

Sometimes with the lamintaions on darker painted surfaces or with darker tints you ll find some tiny bubbles due to the UV powder, so sometimes is better to lam with MEKP cat and the rest with UV cat.

5

Thanks a lot reverb. I think i now have a good understanding of how it works. You have a good point with the problems of tints. Thanks again for the help.

6

2.5% MEKP is kind of a lot, but it depends also on your local temperature, humidity and the "strength" of the catalyst in your area.  Not all catalyst is the same, methinks.

A test batch of carefully controlled catalyst ratio would be useful, as well as keeping notes on your ratio with each batch you mix. Remember too that pot life is much much shorter than if you pour it out on the blank.

FYI here in Honolulu with temps and humidity in the high 70s, I use about 0.8% catalyst for a 20 minute work time.  It would of course go off slower in lower termps.  Test, record, retest, proceed when you think you've got it worked out.

Useful:  1 pint = 473 cc, so 1 pint at 1% catalyst would require 4.73 cc catalyst.  1 pint at 2.5% requires 11.8 cc catalyst.  1 pint at 0.8% requires 3.8 cc.  Get and use a plastic syringe from wherever...

7

Thanks charlie, all very helpful information. I think for my first try at poly im going to do a plain clear lam with UV cure to get the feel for it. Ill give the pigment a try with some catalyst after the first try. I like the idea of some test batches and recording the data, something i will be doing. Thanks a lot

 

Derek

8

…hello Honolulu,

yes there are industrial MEKP and normal ones.

Also in cold weather 0.8 is nothing and the lam resin will kick eventually (not the hotcoat less even the gloss coats) but not fully cure.

I assumed that Drock is in cold weather may be I missread something.

More resin less MEKP, less resin with pigment, more MEkp so small batches test do not determine the total amounts of cat.

The better reference is have the resin catalized for around 10 mins gel time

that s a fine % of cat

You can build a chart with resin brands, cat brands and type, weather, room conditions, etc but with total amount of resin for 1 lamination, then total amount for 1 hot coat, etc. All for clear coats.

After that, think in what pigment you are using (darkness, brand, type) to adjust the %

Yes, there s slightly difference between brands.

 

9

As others said, catalyst ratio is not only dependent on air temp and humidity, but also size of the batch. Poly resins give off heat as they cure. The larger the batch, the hotter it gets. A quart of resin will gel faster in a bucket than if the same amount is poured out over a layer of glass. So, test batches can only give a rough approximation of gel time vs ratio unless you spread the resin out over an area.  The longer a batch stays in the bucket, the faster it will gel in the long run.

10

my advice:

 

  •  use a lot of resin. With epoxy you would use less resin. For example, for a 6´2, if you use 400 cc of epoxy, try 600 cc of poliester. Speaking of a non-profesional glassing. A pro would use less. If it´s your first time, I would use even more, 800cc. Polyester is cheap, so don´t be afraid of waisting. 

 

  • you have to push the resin into the cloth with the squeegee. With epoxy it wets a lot easier, with polyester you have to do a lot of passes and wet it well. 

 

3 key steps that I found here in swaylocks:

1: wet all the cloth

2: fill in with more resin, make sure it´s wet enough

3: take the shines out

 

good luck! 

11

Thanks guys, pretty much what I said.

Drock, you're gonna love UV cure resin.  My first use was a 10' longboard, glassed clear in my garage. Walls on three sides, roof, open door to minimize fumes.  I wear a two cartridge respirator with organic vapor (activated charcoal) cartridges - you should too.  Polyester resin is nasty to breathe, as has been documented on these pages.

I left the garage door open and late in the lam, noticed impending stiffness in the wetted glass at the end nearest the open door.  I got that end stuck to the board, pronto, and from then on closed the door 2/3 of the way during all UV glass jobs.  Which, after that first use, are all I've ever done UNLESS the board is an opaque.  In that case it's back to catalyst for me, but still using UV cure resin.

The need for catalyst in opaque resin is seen when you pinline with UV.  The pinline won't fully cure because the incoming UV sets off the resin only at the surface.  I think surface curing is okay if the pinline resin is also catalyzed as it would let you move on the the next step without having to wait for full cure, BUT watch out, the pinline will not be well adhered to the board because at the surface of the hot coat it will not have hardened.  Simply catalyze highly colored resin, and be safe.

As for coloring your resin, if not opaque you will need to have a near-perfect finish on the blank.  Every minor surform tear will take more resin and result in a darker mark.  The easiest way to approach color work is to do a yellow board.  No matter the amount of yellow, it all comes out well in the end.  Blue and red are MUCH more difficult to get evenly laminated, even with a finely finished blank.

But the difficulty of exquisite squeegee work on colored lams is itself the reason for UV cure - you can take all the time you need to get it right, then drag it into sunlight or flip on the UV lights, and 10 minutes later you're on to the next lamination.  No way I'd try that with catalyst, I like to have my catted boards cure overnight between laminations.  But that's just me.

Another point - the difficulty of exquisite squeegee work, and that a glasser may get a less than perfect finish blank from the shaper - leads to the popularity of spraying colors directly on the blank.  There are advantages to this approach, some significant, but that's a whole 'nother bag of worms.

12

Thanks guys. Im pumped to try it out. I will definitely give the UV a try so i can take my time and learn how poly works. Im going to wait on the pigment for now until i get used to poly.

I have a question about poly blanks. They get softer as you shape them down, correct? Its hard for me to find the right size blanks for the right price here in NY. I can get some 6’8" eskimo blanks but im not sure how short i can shape one without it being too soft. What do you guys think? I most likely wont be making anything bigger than 6’.

 

Derek

13

What part of NY? There’s a number of guys doing poly boards in the Long Island area. Might be able to score a blank from one of 'em.

Isn’t there an outfit in NJ that sells blanks?

Also, the density becomes more of an issue as you shave a blank thinner. So, a close tolerance type of blank should not lose too much as the difference in thickness between a 6’0 and 6’8 isn’t usually that great. YMMV

14

Im on the south shore. Yeah there are a number of shops. Im going to swing by them and see if they wouldn’t mind selling me a few. NJ is always an option. Im just trying to avoid the drive, and the traffic as well as shipping costs.