Greetings,
Was wondering if it is possible to laminate with UV cure and hot coat with MEKP.
Feedback appreciated. Thanks in advance…
Rick
Howzit ephuzol, Using catalyst in your hot coat is better in my opinion since you don't have to worry about the wax not rising plus when using UV for hot coat you need to add extra SA to insure there is enough wax to rise. The thing is this will thin the hot coat and that means it's easier to sand through. I used UV resin for laminating only for years but always used catalyst for hot coats. The best part is after the catalyzed hot coat kicks you can then put the board in the sun to finish the curing process quickly. Aloha,Kokua
…hello Kokua,
happens that MEKP + UV cat H Coat resin is a no way to go with high humidity +very cold weather
occurs that the only way you can cure 90 - 100 % that hot coat is ONLY with UV cat
but never will be completed with MEKP included
sounds incredible but in the last months I did all the testings
This thread tempts me to add another question that hopefully Kokua (or someone)can help us both with. I have a very skilled mentor for glassing advice here in my hometown who has always put me on the right track, but this bit of advice he gave me re MEKP v. sun cure leads me to question this advice.
He says there are two aspects that need to be considered, one being the convenience of construction and this is the angle that Kokua seems to be coming from. But also my mentor says is wise to consider the mechanical properties of the board. Specifically, that you will get better tensile properties in your board if you use MEKP in your laminates, but only if your glassing schedule isnt to heavy.
This is apparently because , when using MEKP, it pumps the styrene out of the resin causing the resin to shrink and therefore tightens the fibres in the cloth, giving a tighter tensile flex than if you used sun cure that doesnt pump out the styrene.
What makes me wonder about this is knowing that sun cure sets so quickly, and thus surely it pumps out styrene even quicker, so logic says that the fibres should be even tighter. My mentor says that sun cure doesnt pump out the styrene and thats why the smell of styrene vapour isnt so evident in suncure. He reckons suncured laminates just sit there and set in a benign way without tightening up the fibres. He recommends suncure for the filler coat only.
If this is true, what does happen to the styrene in suncure. It has to go somewhere in order for the resin to set, and wherever that is, it must go there quicker than an MEKP cure. If so, why does the MEKP laminated board feel springier in the water than a suncure, when all other variables are the same ie, Bennett yellow foam, Silmar resin, JPS cloth 2 x 4oz top/ 1 x JPS 4oz bottom, with shaped blanks of same length, curve, thickness and width.
Can someone advise me on the physics and chemistry going on here. I cant help but wonder if
a, Ive got crook advise, or:
b, Im labouring under a delusion…
Any advise is appreciated!!
I dunno about the chemistry stuff, but the makers of the sun cure additive I use claim that it is stronger and resists yellowing better than MEKP laminates!
http://www.soltekonline.com.au/
I have no idea if this is true or not.
They say that MEKP is partly to blame for poly boards yellowing!
In the past I was always told that a board that cures slowly with MEKP has a chance for the polmers to cross-link more competely, resulting in a stronger, less brittle structure.
But suncure sets so fast, something else must be happening there?
Reverb,
If you come back to this could you re-write your response please? I didn’t understand what you were saying. I mix my own sanding resin. Lam resin plus sanding agent. I always put bit of catalyst in it, too. I let the board sit a few minutes before I pop it in the sun to let the wax rise. I learned( I think from Kokua a few years ago) to add mekp to uv sanding resin because I had gummy hotcoats on a couple of boards. Mike
…Rooster,
that MEKP with UV work good in “normal” weather
but with a very cold weather + High humidity for weeks you never have a proper Hot coat, less a Gloss coat
always gummy
so, I proved that mix
but doesnt work with a weather like this
so the safest way is not put MEKP, because the main problem is more in the MEKP than in the resin
or change to a hotter MEKP, but its almost the same
so with Mekp you ve got a reaction but could be not finished ever (the cure process)
-we cant put a board to a higher degrees to finish the cure-
but with UV cat only, you can obtain a healthy 90 - 100% of cure in that weather conditions
Edit to clarify that seems that the resin “take” the Mekp and not the UV cat to start and finish the reaction
so no matter if then you put the board under the Sun, it will not be cure
Howzit reverb, Well that's news to me since I've done them with 100% humidity, raining and in the 60's temp wise with no problems. Aloha,Kokua
…Kokua, more than 10C outside and an artificial of 15C inside
but for weeks (thats may be the difference…)
Reichhold resin
also, with that weather all the lam resin brands that I used, tends to whitenish (becomes White due to the humidity)
and the Hot coat resin evaporates too much styrene and with less than 15C for weeks, inhibiting it is a fact
so is very difficult to obtain a proper polimerization
in my opinion, if putting MEKP with that weather, you need to put too much % or a hotter Mekp; so reduce the gel time
but not produce any change in the final cure
only if you put DMA, but change the color; so with that little time you brittle the resin and have not time to rise the wax so the surface always be tacky
plus, sometimes never will be hard (always gummy-and too much styrene odor)
and if you put low % of MEKP, in all of my test brings like a useless thing
-I obtained better results with only UV cat and no add of MEKP
Howzit reverb, On Kauai it can rain for months at a time so the humidity can be very high and it never gets below around 70% to begin with. The only thing I notice when it's high is my sand paper gets limp due to the paper absorbing moisture. As for my mixtuers I never change them no matter what the weather is doing. I won't laminate during high humidity since the blank is also absorbing moisture and that's not good.Aloha,Kokua
Regarding Hotcoats…if you are working in extremely cold conditions with high humidity just heat up the room first with a portable heater.Shut it off and shoot the hotcoat.Even when not using suncure resin I can make a good hotcoat go off in 15 minutes max with a good wax rise.One reason for a defective wax rise is putting the hotcoat on too thin or messing around with resin (overbrushing).Also…I don’t know about the chemistry either and have never even heard of “pumping the styrene”.Thats a new one to me. R Brucker old school.
Howzit Mr. Clean. The record low for sea level in Hi is only 53 degrees and that's nothing compared to other locations. Adding extra SA to UV resin when using for hot coats was something I was told when I first started using UV. They advised this to insure there would be enough wax to bring it to the surface but it does thin the resin and after 2 times that the hot coat came out tacky I went back to using catalyst. My hot coats are like yours in the fact they go off in 10-15 minutes also plus with UV resin after the hot coat kicks just put the board in the sun to cure so I really don't see any advantage to just using UV for hot coats. We think a lot alike.Aloha,Kokua
…hello Kokua,
like I said in the other comment, I think the difference is in the places
not equal a tropical weather than a place that is very cold with high humidity for months (that is a nightmare to do perfect gloss coats)
I glassed in most conditions except in a tropical weather, so I dunno
-for ex, today I did a ding repair with 75% humidity and 17ºC (pre heating the resin and then pre heating the resin+MEKP without UV cat) and the lam resin becomes White (due to the humidity) …so then I forced warm air via heat gun to get rid of that whitenish thing
… hello Cleanlines,
like I said in previous comment
I heat up the room always, I heat up the resin, I heat up the board (if I m doing a Hot coat, gloss coat), I heat the MEKP (that does more problem with humidity than the resin)
etc
Im no newbie glassing boards and obtaining very good results in gloss coats in the worst scenarios
by the way, when the resin tanks cross the Equator line in the cargo ships for days, this thing kill the resin
is not the same when arrive (if not arrive fast) in the South
so Reichhold and other factories try to not do that and they have plants in different Countries (among the $ involved)
In 25 years I have been using Reichhold, Silmar, Resapol, Cray Valley, Elequeiroz, to name some
–I made this one in not so good conditions, but obtained a normal coat (only with MEKP) then I used all the “technique” to not have any swirls or wheelmarks
