Help with First Lam and Long Air Bubbles along Rails

So I just finished laminating the bottom deck. This was my first glass job. I had read plenty of articles and watched tons of videos so I assumed I would be able to do it easily. Well…as you all know everything didnt go as planned the first time. I didnt tint the resin but just painted directy on to the foam. I was rushed along the rails so I didnt have enough time to fully saturate and the lighting was off so I wasnt able to see that great. I have long air bubbles along the rails. I have read a few different things like getting syringe and injecting resin or cutting it out, sanding down, and patching but I am not sure how to fix this error. I am using PU blank and poly resin. 

How do I fix long air bubbles along the rails? 


The problem looks to me like the result of too sharp a corner along the rail combined with not babysitting the lam.  You probably had the glass down but it sprung back because of the sharp rail. 

I haven’t had any success with injecting resin, if it were mine I would hand sand just until I got through the glass, then work some resin in and patch with glass scraps, sand flush, and it’ll be covered by the next layer. Or I might omit the glass patch if I were going to have 2 more layers of rail wrap. But I work with epoxy resin, there may be a different approach called for with polyester resin.

Then next time I would put a little more radius on the rail and square the edge with a resin dam at the end. Fiberglass cloth really doesn’t want to turn a hard 90 degree corner.

Huck’s advice is the best way to go about repairing it.  I suppose that if you damage the paint on the foam while sanding you may be able to touch up the paint before glassing.  A touch up will show.  Sand by hand and try not to go below the glass. You might be better off to attempt cutting the bubble out with a razor or Stanley knife.  What was your  MEK ratio to resin.  On a lam like that I would be looking at 10cc to one quart.  Less MEK yields more working time.   You have to baby sit hard edges and rails.  When it starts setting you can use a hard plastic squeege and your finger to continuously go back over the rails.  I run my finger along the edge pressing down fairly hard.   A lot of times you will have wait,  press it down and wait, press it down and wait, press it down.   Another trick is to flip the cloth up before lamming and brush uncatalyzed resin unto the foam along the rail.  This will make the cloth stick during the lam.  The uncatalyzed resin will blend with your catalyzed resin when you are working the lam with the squeege.  Work fast when you Lam.  Pour and spread the flats once and then go to the rails ASAP.  Once you have got the rails you can double back and work the whole thing.  Insuring saturation and pulling off excess.  Lowel

PS –  I’m compiling statistics.  What cloth did you use?  Hexcel?

Thanks Huck! I went with the razor technique. Its tricky but it may end up working out. At what point is the resin and fiberglass actually ready to sand? It has been a few days and there are a few sticky spots and when i sand its gummy. I appreciate the knowledge and info.

Thanks for you advice McDing! I am using Aerolite 6 oz standard. So I glassed the board a few days and after I cut the bubble out with a razor, I tried to sand but it was kindof gummy. There were some sticky spots still on the deck. Is that normal? 

As far as what my MEKP ratio was, I am not exactly sure. I used Ding All Lam resin and they provided a harderner that you drop droplets in. I did around 12 drops in the resin. 

Thanks in advanced.

Yeah that’s why I pointed out that I work with epoxy - its a little different. You can sand every coat. Its been a long time since I worked with poly, but as I recall the laminating resin stays gummy. 

The laminating resin will remain tacky to the touch but it shouldn’t be gummy or have sticky spots. How much resin did you use with those 12 drops of catalyst? Sounds like you may not have used enough catalyst.

Once you’re done with the lamination you need to use sanding resin for your hot coat. It’s lam resin with surfacing agent (styrene with wax). This will allow you to sand normally without clogging your sandpaper.

Yea, I think you are right in that I did not use enough catalyst. I used around 24 oz of resin. Thanks for your help! 

Yeah that’s not much cat at all for that amount of resin. That may have contributed to the problem, like Mcding said you have to baby sit those edges sometimes to keep the glass stuck until the resin starts to gel a bit.

Yes you have to “finger” it a bit.  I start my lam with a Thalco squeege, then go to a 4 or 6" Plastic squeege.  I lay off and saturate with the Thalco, start the rail, nose and tail.  Then I go to the Plastic squeege and use it to pull off excess resin and pull the rails, tail and nose down tight.  Then I babysit it with a 4" plastic squeege and my finger.  So 24 oz. is equal to 1 1/2 pint of resin.  Less than a quart.  I use 10cc to 15cc per quart or 1 1/2 quart.  You guys do the math for me, but I don’t think 12 drops is enough MEK.  The most you can do when it comes to sanding lam resin is to grind the edges or laps.  You can do that with a die grinde and a 50 grit disk or some good 60 grit Indasa sandpaper and a block.  But it is too tacky to really sand.

PS--  A small cotton paint roller works well for saturating rails as well.  

12 drops is not even 3/4 of a cc according to the Fiberglass Supply chart, yeah not much, hopefully it cures for him. 

That Indasa paper is awesome, I just started using it, man that stuff just keeps cutting. Couldn’t belive how long the 220 was effective sanding hotcoat.

Thanks for the good advice! I went ahead and did the top layer and it turned out alot better. I followed the tips and they worked well.


Related: I had to pick up some unbranded cloth from an industrial supplier to finish my board the other week. It was a really, really different experience to the cloth from my supplier - it was springy in parts (wanted to spring up when wet out), the weave warped in a few parts just from wetting out, really hard to wrap the rails, hard to laminate down. I had to work it for about 20 minutes just to get it to stay down, and it didn’t seem to hold as much resin as regular cloth.

Is this to do with some form of treatment? I’ve heard that some non-typical cloth is sprayed with something. I won’t be using it again, but I guess I’ve learned that not all cloth is made equal …

I have had similar experiences. I would ask the industrial supplier for a techical data sheet for the cloth. I went round and round with a local supplier to find out whether a cloth he sold me was ‘silane’ or ‘volan’ or ‘direct sized’. Some of those might be tradenames. Turns out the cloth I bought was a chromium treatment so more like ‘volan’ whick explains the greenish cast to it. I have another batch of 8oz I horsetraded for that I think is direct sized. I call it ‘mystery’ cloth. Probably better suited for boats than boards. My local shop is not ‘surfboard’ ready with materials like Hexcel or 249A or surfboard grade epoxies. They are more boats-race cars-industrial. Nice people though, I try to stop in and say hi when I am in town and buy a few odds and ends. If I have a fin or something small to show and tell I bring it too. I blew their minds with some RR Kwik Kik, the last ounce or so from a lam left in a container to set up. They had never seen an optically brightened epoxy, they were used to the darker boatbuilding types. They did get us through our first couple boards with cloth, resin, squeegees and stuff, until we got hooked up with mail order surfboard grade supplies.