hot coat or filler resin- catalyst ratios in mls

how many mls of filler resin to mls of catalyst, if i used 25 ml of catalyst to 300 ml of filler resin would that be alright

depends on weather and a bunch of other things... do a small test batch and try to get the resin to kick in about 15 min. not too fast cause you want wax to rise but not too slow cause you don't want resin to drain off board. 2% is a starting place.

Hi 3paw,

the ratios I use are: Slow Cure (about 25 mins to gel) 1 mil of catalyst per 100 mils of resin.

                                Reg/Normal Cure (about 15 mins to gel) 2 mils of catalyst per 100 mils of resin. Which is, as astevens says, 2%.

                                Fast Cure (7-10 mins to gel WORK FAST!) 4 mils of catalyst per 100 mils of resin.

Of course these cure/gel times will change depending on the weather. If its a stinking hot day (28 to 30+ degrees celsius) when I'm glassing I always go with a Slow Cure mix as it will gel quicker in high temps.

Average temp days or cool days I go with Reg/Normal Cure mix. As I live in Battersea, England & the temps are predominately cooler (than say Sydney, Australia where I come from) I mostly use the Reg/Normal Cure mix.

Have Fun Mate!

Hi again 3paw,

I should have also said that, as you are asking about hotcoat/filler resin, you can probably go with a Reg/Normal Cure or a Fast Cure even on a warm to hot day as you'll be slapping it on real quick with 3" or 4" brush so your actual work time will be around 5 to 7 mins. Then you'll be hanging around waiting for it to gel so you can pull your tape off.

Have fun Mate!

Thanks apauly1954 for your advice, but i had already attacked it . it was pretty cold (12-15 degrees)  so i upped the dose of catalyst ! 350mls of filler resin to 25mls of catalyst, because i did want to go off fast. here,s what happened, it started to gel in about 5-7 mins and now once it has gone off the surface is all sticky/tacky or waxy maybe? when sanding it  the pads just clog up and it doesnt really sand anything. is there any come back from this or am i stuck with unsandable surfboard. i thought maybe wet and dry sanding it? cheers mate

Sounds like you over-brushed it. Once the resin starts to kick and the wax rises to the surface, you don’t want to disturb that surface. The wax forms a barrier to air and allows the resin to harden fully. Too much brushing will prevent the barrier from forming and the resin stays tacky indefinitely. I learned this the hard way when I first started glassing.

The only way to recover from this condition is to do a fairly thin hotcoat and make sure you DON’T brush too much. It will then be sandable.

Another cause of sanding resin not drying hard is applying it too thin.

There’s also the obvious question…

Are you sure you are using sanding resin?

It takes at minimum...5min of uninterupted(not using the brush) time for the paraffin to rise to the surface. so if you kicked youre resin in 5-7 min and it took you probably 3 min or so to lay on the hot coat, then you did not let the wax rise. Don't go to the other extreme and under catalyze your resin because it will all drain off the board and defeat the purpose of a hotcoat.

 you have an easy to fix problem though. do another hotcoat on the otherside... this time do not make the same mistake. next, flip the board over to the side you messed up on and do another hotcoat maybe add a little bit of styrene to the mix in order to thin it out on the board. you might have to sand a bit extra but the second hotcoat should go on VERY thin. good luck and i hope this helps you

dont worry SammyA i have wondered that myself, i purchased it (separately from the lam resin) from the supliers and it does say filler resin. unless old mate has mixed up the containers when he filled them?

Thanks astevens for all your advice, you have hit the nail on the head mate, cheers

how did this go mate, Im reading this thread in interest.

sanding resin and temp could be your prob too. if the wax is cold it will chuck up and not work well. I use lam resin and put surfacing agent in the resin myself. before though, I put the SA can in warmish hot water to get rid of paraffin chunks. the end goal is to have a hotcoat with a matte/dull film on the surface. this is the wax. good luck but you have probably already done thehotcoat so this may be too late.

Hey 3paw,

I also use laminating resin & add my own 'wax in styrene' which I buy in 125 mil tins. In say 500mils of lam resin (which is enough to hotcoat a 6'6" to 6'8" performance board or fish) I add 60 mils of the 'wax in styrene'. It works perfectly every time, never had a problem even when using a Fast Cure mix. The wax rises as it should & sands beautifully. In fact I've done a few boards which guys wanted really lightweight with just the hotcoat/filler coat sanded, wet & dry papered (done wet of course with some dishwashing liquid in the water) & not given them a gloss finish coat & they are perfectly smooth & look good too.

So what I'm suggesting is see if you can get the tins of 'wax in styrene' (it is what it says on the tin) & try that rather than using the filler resin (which I have used in Australia, but have not seen elsewhere in the world. Its certainly not available here in the UK)

Cheers,

Paul

Yeh mate I have just gone that way, i brought a 20ltr drum of lam resin and some wax in styrene. I was just tring to use up of remainder of pre mixed filler. Now i think of it i had a similar problems on other boards, i might mix it myself in future, thanks Paul

think i will go that way on the bottom. Cheers

well mate i havent filler coated the bottom yet but the lads where spot on with their  diagnosis. as far as fixing the top, i have started sanding it with 80 grit wet and dry, and that has taken the shine off , i will try again to sand it before i recoat it with another filler coat, hopefully it will sand better, i'll get back to you in the next couple of days