10 Questions You Should to Know about pu coating catalyst

Hi guys,

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This is my first post, although Swaylocks has been part of my daily routine for sometime now…

I’ve managed to shape my first 2 boards, both from PU blanks, a 6’0’’ fish and a 6’2’’ shortboard.

I’m now finally getting round to glassing them and I have a few questions I’m hoping I can get some advice on…

1. Regarding correct amounts of resin vs catalyst, some sites/books base these amounts on board length purely, others base them on board length, board volume (litres), humidity, temperature, etc etc, making me even more confused… Are there any “definitive” rules of thumb when it comes to knowing just how much resin to mix with just how much catalyst?

2. Regarding types of laminating resin, there seem to be quite a few types and brands around, and therefore varying prices, and I’m assuming varying degrees of quality? In your opinion, is resin just resin (and hence, get it as cheap as possible), or do you advice steering clear from the cheaper resin due to poor results?

3. Lastly, once deck is laminated, how long is it recommended to wait until laminating the bottom?

Thanks all, apologies if these questions have been answered in other threads already…I have searched quite extensively but not getting the answers I’m after…

Cheers,

Gabriel 

Yes 10cc in a quart is plenty. It will kick but should give you enough time. UV is the way to go however. I would strongly recommend it to all newbie glassers. I’m hooked and only use mekp for specific purposes now. I had real issues wetting the laps on my first few boards  with mekp. A long time glasser gave me some great advise. He told me to quickly wet out the flats only pouring out what was needed as i went. Then I used a 4 inch paintbrush (cut off approx 1 inch of the bristles first to make the brush stiffer) quickly dip the brush in you bucket and wet out the laps sort of half ass tucking them as you go with the brush be liberal with the resin and move quickly. Soon as you make one pass around… grap your squeegee and tighten the laps pulling out the resin (don’t pull too much or you’ll end up with dry spots). Rather some extra sanding than dry spots. You can clean up the drips and runs as you go, but once it starts to go off you’re done.  Planning is everything…have all your tools ready to go and with reach. Lay everyting out in order of use and so you can pick it up with goopy gloves. I wear light gloves so I can put on two pairs. As things progress and I start to get resin all over me I strip off the first pair. A small bucket of acetone ready to go is a good idea also… if you drop your squeegee and it’s the only one you’ve got… rinse it off quickly in the acetone and keep moving. Planning…lay it out…rehearse the steps…check the time…do it again before you committ to resin with mekp in it…not everyone here will agree with what I just said…lot’s of opinions… but these are the basics. Watch some vids on you tube…those guys are pros…it will take you twice as long!

First I want to say. You glass the bottom first then the deck. 

Now mix up some resin on the slow side half of what ya think you need. That way ya have some time to work. Then after you have everything tucked and wrapped but not totally cleaned up you can make a small amount up hotter and give it a cheater fill coat. Now that you mixed in all that hotter batch of resin you may have lots of drips falling off your rail. You have the bottom all even work the resin in to the rail with your fingers pulling from the middle towards to the nose then from the middle to the tail. Now take your rubber squeegee and pulling from the “middle” of the rail to the nose and then the from the middle to the tail. Remember never pull your rubber squeegee  against the weave on your lap. Remember the weave is cut to the nose and the tail inward. The last thing I do is at the end and I think its all clean and done I grab my Lam brush and look for any drips I missed or a any dry spots. A lam brush is a 2" brush I cut down to very short bristles about half. Good Luck and remember bottom and then the deck. 

Thanks heaps guys - much appreciated.

Ok, I bought the Shapers Surfboard Laminating Resin, and the Shapers U.V. Sunbake…will mix 1 quart + 10cc per side of the board right?

@nj_surfer - thanks mate, when you say that “experienced glassers whould shudder at using a quart”, do you mean because it’s too much or too little? (From your wording, I take it a quart is MORE than I would need right…?) Most of the guides that I’ve read recommend using 2 quarts and more PER side of the board…To me (newbie) that seems like A LOT of resin…How much resin do you reckon experienced glassers use? Just for reference…

You will get efficient and thoughtful service from Yourun Synthetic Material.

@woddy - thanks for tip, yes I’ve actually watched a few videos where they do exactly that with the brush on the sides…will definitely give it a try.

@sanolocal - thanks for the advice - what do you mean by a “hotter” cheater fill coat - is this always necessary? I’m taking that you are not referring to the hot coat right, or are you? Also, would you apply the same measurements i.e. 1 quart + 10 cc to the mix for the cheater fill coat?

Cheers.

Its just a second batch that is mixed hot more cat. Then after you did all the laming and the rail are tucked pour out that hot batch. It will help the first batch kick and fill any air you may have left behind. This is not how I do it but it is a safer way of getting the job done without the stress of " OMG is it going off". Take your time speed comes in time. For a shortboard on a normal day 72 lets say. I would use about 18 cc and about a 1/3 of a small bucket. If you do it right and have some resin left enough to cheater it then add some more cat to that first bucket and finish. Just remember to clean your rails up good. if ya get done and ya have a few dry spots mix up some more resin in a cup and touch things up. If you let the rails go off before you clean them up your screwed. If for any reason it goes off on ya in the middle of you lam "Pull the cloth and clean the foam of the old resin before it kicks. Better to save the shape then the cloth and resin. You would have time to clean up all the messy laps. But you can clean the blank in half the time. Take your time and and give yourself some time and you’ll be fine, but if in doubt then ya need to pull out. 

Dont you guys worry about using sun cure resin on a whole board? i keep one of those little toothpaste bottles of SC around for if I ding a board and need it the same/ following day, but I always pull it out and refinish the ding with regular resin. in my experience using both kinds of SC for ding repairs, it always tends to yellow and crack very easily, I wouldnt want to risk it on a whole board.

As for the lap, with very little practice (if you mix a little extra resin for all the extra that will run off) you can just lightly pull up the extra lap and our right along the rail line, first getting the majority of the lap for each side generally soaked, then going back dragging the squeegee along the rail line to push excess resin onto the rails to fully soak it… just dont try wrapping the rails until the whole side, or most of it, is soaked. A lot of people will say to do other methods for rails for beginners, but honestly, if you mix extra you can always just pour a bunch of resin straight on the lap when you hold it out and it will all soak in… better to learn the right way and deal with a little bit of ‘omg, this is gonna harden on me, i’m screwed’ than not learn it the most efficient way out of the box. 

I’ve used several different UV curing (premixed) resins and several different additives to make silmar resin in UV. Never had it yellow. As a matter of fact I think it’s brighter, clearer and stronger. The scientists on here can explain it better than me but ultimately it has to do with the chain reaction of mekp vs. the whole batch literally going off at once with the UV. I have had such success with it… I built a UV curing booth so I can manipulate the curing process even more. I have heard that some guys experienced problems from just adding the normal amount of mekp to premixed UV. This isn’t a good idea. Only a very small amount should be used under logo lams and such.  I always use regular lam resin for repairs, fin plugs etc.

My logo is a six inch circle made with opague colors so the UV rays can’t get through to cure. I have tried several methods to deal with this. The best way that I have found is to roll back the cloth where the logo will go and then laminate the logo on with a very small batch of silmar with a few drops of mekp. I baste/paint the bottom of the logo first on a peice of wax paper, apply it to the board and lightly squeegee out the excess. Then I paint the top and skim it as well. I leave it for 5-10 min. and then roll the glass over it and go with the UV as normal. Again you can just mix a small 2oz cup with the premixed and add just a couple of drops of MEKP to accomplish the same thing. Remember I’m talking a couple two to three drops…not squirts with a bottle!

I am really unsure whether it is worse to hijack an old thread or start a new one for potential newbee questions, so I chose to go this route…

I am in the process of building my very first board and will soon have to think about glassing. Since I am stuck in Germany with little surfable waterfront there seems equally little access to shaping materials. the few online shops who have the necessary stuff sell it for big bucks letting total cost for the board escalate far to quick. so I went on ebay to search for “cheaper” alternatives with equal quality. I came up with these two for resin and cloth. Maybe someone can point me in the right directio whether they make any sense and if not where I should be looking…

1. http://www.ebay.de/itm/3-25Kg-GFK-Epoxidharz-Epoxydharz-Epoxi-Laminierharz-Terra-Harz-Top-Qualitat-/?pt=Kunststoffe_Chemie&hash=item58bad

2. http://www.ebay.de/itm/?_trksid=p.m.l&ssPageName=STRK%3AMEBIDX%3AIT

I am aware that the describtion is in german, but the technical details seem to be fairly universal (I hope). My biggest question would be what kind of cloth makes sense for a surfboard. I am shaping a PU blank by the way…

thanks everyone,

Sebastian

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