Gelcoat mixing additves?

OK
If you cant find Styrene then use acetone !! ALWAYS use in moderation !!!For spraying keep it down to no more than 5 % of the weight of the gel coat that you are using .
When gel coating remember to Catalyse at 1.5 % as a absolute minimum and no more than 2.5 % as a maximum.
With most polyester resins the safe working ratio is .75 % As the absolute minimum and can go to 2.5 % as a maximum .
Be accurate!! weigh the gel coat in a plasitc container on some scales so you know how much you got , go and find a measure thats in cc or mils and work to the ratio that suits your needs . DONT LEAVE THE TOPS OFF YOU CONTAINERS WHEN YOU USED THEM Start at 1% catalyst with you resin and increase if need be !!
Start at 1.5 % catalyst for you Gelcoat and see how long you got to work with it .
Thin your Gelcoat with acetone if spraying !!! if rolling try a little resin in the gel plus a small amount of what you call airdry like 2 %, but be accurate with all and every mix you do !! Sound like the air dry is a styrene wax solution . The wax floats to the surface of the gel coat to stop it from being sticky when its hard . Remember the wax'y surface needs to be scuffed or ground if you want to go over the top again with gelcoat or resin . or you will end up with a peeling problem later as the resin or gelcoat wont stick to the waxed surface properly .
Gel coat and resin need Catalyst to make it go hard!!! Mix everything well and properly . Temprature plays a big part in the speed at which any of the resin or gel coats go hard also humidity !! High humidity can and will slow down the reaction of the catalyst . Any water or excessive moisture can and does kill resin and gel coat and it will not go hard like as in never !!!.
This info is absolute basic for any thing you are doing be it gel coating , spray of rolling , or laminating with any sort of polyester resin .
Its real easy to remember !!!

A splash of this and dab of something else is no good , Think a little use that gray matter under the old hat rack .
MEK IS A THINNER but dont use it, its not nice and very smelly.
MEKP is the catalyst you use to make your gel coat and resin go hard . The same catalyst can be used for both resin and gel coat but most times they are differant for each .
Here in China is the only place in the world where ive used the same catalyst for everything .

 

Thanks,I did assumed MEK was a solvent thanks for rectifying that.My catalyst for my poly resin is MEKP says right on the label.Im heading out to the shop now and I will take a picture of this gelcoat catalyst they gave me its a different product and I will ask what would be better for me to use.

 

Thanks Tunnels,I just read your post just after posting 17 and I do practice exact measurements and agree it is crucial for consistency,done my share of autos.I have the perfect kitchen scale that goes to 8lbs that I can use,this will be the fist time I measured by weight,not a bad idea just for the gelcoat of course.I have left the tops off a couple of times in a hurry to get the job done,gotta stop that, good tip.We have a couple body shops around here and I check too see if they have styrene if not I will use a min amount of acetone to spray.

 

The trick to using acetone is spray a thin coat, then blow a little air across the surface!, spray again and more air across the surface !, Keep doing this till you get the thickness you looking for .
More than 90 % of the acetone is gone as it leaves the gun and before it gets to the surface and after a blow job there almsot nothing left . Its only added as a thinner and get the gelcoat through the end of the nozzle, thats all .
Now styrene has another set of problems to be acreful of , One it dosent evaporate the same as acetone so becareful of runs and it dosent cover as well !!! Plus the UV light makes it yellow off over time !!
I know which one i will keep using for ever more !!.

MEK i would never use , i hate the stuff ! the smell is just to much for me to handle !!.

Check the catalysts for resin and gel coat and mark you containers with a marker pen !!.
Why are they differant ? Gel coat when it is mixed with catalyst starts a chemical reaction and semi foams ( microscopicly ) Its the amount of foaming that the special catalyst helps to minimize !! thats why it used , plus it gels better and harder .

Here in China we use the same catalyst for everything and have a load of problems , takes 2 hours to go hard !!!, 2 hours for God sake !!! and i never seem alligators or shrinkage and pre-release like these guys get . simply because they use the wrong catalyst !!

Keep up the weighs and measures !! good for you !!

 

Guys,Here is the catalyst they gave me,can I still use this product as if it was MEKP,same ratio.thanks

 

It is MEKP !!! possibly the same as what ya had before . Look down the bottom of the lable and see ya MEK

The "P" makes all the differance specially when ya need one

 

That catalyst will work fine for both products (resin and gel coat), most the blends and other catalysts that may not work well with gel coat aren't really available on the retail market. Well you could probably get them if you asked specifically for one, but they may need to special order it and you would probably need to at least buy a full gallon, maybe even a case.

 

Great, OK now I know what MEKP stands for,I missed that .The stuff I have been using just says MEKP for polyester resins.Super!! Im set to do some serious gel coating now.Thanks everyone, very much appreciate all the advise.

 

Good to know ONDARVR.I was worried that the ketone in LUPROX may not have been the same as what I was using.I feel assured now that it will work fine. thanks