Hot Coat rail sag

Hey everybody, I am pretty new to the forum and pretty new to the world of board building. So far most everything i have learned has come from this great forum and its dedicated members. The rest i have learned from making mistakes. I have now shaped and glassed about 9 boards and i am fully addicted!  I have done a search in the archives under every term or phrase i could think of for this one but have found nothing so here goes:

For all you resin junkies out there in the forums: every time i have done a hot coat so far i get these little canyons or crevices on the deck right where the rails start rolling down.  Its like the resin on the deck stays put but the resin on the rails starts flowing off and then splits away from the rest.  I know there must be sombody else who has experienced this and also somebody who has figured out some great trick to avoid it or get around it.  I am using poly resin and a 4" chip brush to apply the hot coat over the lam.  I really appreciate anybody who might be able to shed some light on this business.  Thanks for looking! -Andrew

Lay it on thinner and kick it hotter.  That will fix it.

A hotcoat is meant to be hot and go off fast.  Make sure you are using the proper amount of catalyst for the amount of resin you are using and make sure your room temp is up there.  I like seventy degrees.  Work fast.  Pour it on and use your brush to spread it around.  After you spread it around do diaganol cross strokes from tail to nose pulling off excess resin.  Then do a fine lay off length wise.  Sounds like you are leaving too much resin on the board and not getting it hot enough.  Remeber room temp is key.

Thanks very much for the help guys! i will try to thin out my coat on the next go around.  So i used about 2.5cc of mek in about a quart of resin for the hot coat.  Is that way to little? Im still gettin the hang of using resin so i was trying to allow for a bit more working time.  Thanks again!

2.5cc's or do you meen %

cause if cc's ,,your way off

edit.. whats your temps at?

you need things to be warm

resin will shear itself on the slopes when cold and too thick.

as Gene and Mcding pointed out ,,  you want warm and a fast kick time

if you go UV cat with mekp you can flash it in the sun when its level and get it to gell slightly ,, no more splits.

I get this on some of my gloss coats when its cold out, I tend to push it sometimes.

Well i have been doing all my resin outside in my shed.  The temp tonight when i was doing the hot coat was around 55 i’d say.  So how many cc’s would you be using in a quart of resin for hot coat? Is it all about ambient temps? It’s warmer here in the day but i do a little work here and there when i have time and most of that time is at night… Thanks for the help!

Like I said; Get the room temp up or work during daylight hours and use UV as Ken said.  Too little catalyst.  You need  five times that amount.  I've used as much as fifteen cc's for a quart.  Gotta work fast but it sets too fast for sags.

55 Deg,,!!!!

man your pushing it

Warm resin on a cold board is not the best way to go

on a good day I use 15cc of cat or half a shot glass per Qt.

I'll bet Kokua is cracking up

if you get the splits just leave them and fill in the valleys after it gells good

Sand till blended

move on

lol, well its definately not the first unorthodox thing i’ve done. Maybe i will invest in a space heater…  I really appreciate all your help guys.  

Ha!  Never thought of using a shot glass.  Could get confusing for a drunk though.  Based on reflexes a guy might down it thinking it's a shot of Vodka or Tequila.

No joke that.  Or then again… Friend’s alcoholic father one hung over morning staggered into the bathroom and hit the Vizine.  Plink, plink.  Blink, bli-- OH Shit!!!  Turns out, some of the kids had been playing w/ the Super Glue that comes in the little tube and left it on the bathroom counter.  They did manage to separate his eyelids at the ER w/ no harm done.  Well, except for his liver but that wasn’t from the Super Glue.

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Ha!  Never thought of using a shot glass.  Could get confusing for a drunk though.  Based on reflexes a guy might down it thinking it's a shot of Vodka or Tequila.

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yep

those little 30ml/cc cups are about the size of a regular shot glass

 

be carefull Lowel

You are using a QUART of polyester resin for a filler coat??? That would be enough for a 16foot SUP.

Also, adding extra catalyst is for the pros in the factories where turn around time is profit. 

Using extra catalyst to compensate for ambient temperature is for the experts who use polyester resin. The experts I know work in teperature controlled facilities.

A one at a time back yard builder applying a polyester filler coat called a HOT COAT(which is polyester lamination resin, styrene and catalyst) does not  need to use extra catalyst in a properly heated glassing area. A hot coat is not called “Hot” because you double down on the catalyst and it nukes out. A hot coat is a polyester resin filler coat. Adding extra catalyst is for quicker turn around times and not for a better result in filling the weave.

Can’t wait to hear about how your polyester gloss coat goes.

 

More examples recently here how polyester resin is way more complicated and confusing versus epoxy. EPOXY: 1 resin/ 1 hardener used basically the same way for every step of the board building process no matter what the foam type or fiberglass used.

 

Now I’m confused

Sounds like you're an epoxy fan bb

Sounds like you're an epoxy fan bb

Ok so i tried the tips about using more Cat.  and getting the coat thinned out with the brush.  The results were about 90% better than what i was doing before. no more canyons and splits!  now i just need to keep working on my brush techniques to get the coat as smooth as possible i guess.  BB30, im not entirely sure im using a whole quart for the filler coat and some of the resin is definatley on the floor when im done.  Since im very new at this i would rather be using a bit extra than figuring out im short half way through applying the hot coat. Thanks for all your tips and advice guys you rock! -Andrew

soooo,,, how much cat did you use?

i ended up using about 15cc’s for what i thought was probably a bit less than a quart. it kicked pretty fast and no seperations on the rails! i still gotta figure out how to get it super smooth though.i still got little bumbs and stuff. but over all a vast improvement for sure!

If you’re glassing in a cold climate be carful using to much catalyst as it will make the glass brittle. The problem can be over come by prey heating the filler/hot coat resin I use a bucket of hot water and put the resin in there in a sealed container then leave it sit for 15 mints  then only add the recommended amount of catalyst. The resin will  be runnier and a lot easier to apply and also flattens out allot quicker than normal and helps the wax rise better. I have also found the bubbles in the finished glass are almost non existent. I know this is a strange approach but it dose work. GOOD LUCK!