Gelcoat application

[dlogvine]

Today I tried to spray gelcoat first time (in my life). So first of all I made sure my cleaning liquid was at hand and ready for use. Next I made sure I can measure resin hardener ratio correctly. Felt like counting drops was a really crappy idea, I decided to do it mathematically correct using percentages. To do this I got a measuring syringe, they are free at any pharmacy. Next i found a conversion rate from ounces into mL, 29.5 mL in one fl.oz. Then I measured 2oz of resine and multiplied this by 29.5 and then by 0.015, got 15%. Same way calculated 10% for styrene gelcoat thinner and mixed it all. Couple problems I encountered. I did not shake the resine well, so got a top layer from the container that had no colorant, so I got a clear spray. Will see if it will turn white when it hardens. Second problem is at the time and temperature. I started spraying later in the evening when temperature dropped to little over 60, from about 75 earlier in. Will see how it hardens over night.
Now I have a couple questions, gelcoat I purchased contains wax. Should i use it or get the one without? Second, if the label said white gelcoat, it means it should be white when applied or does it turn white when hardens? And if it should be white when sprayed, do I just shake the container to mix it up? Do I need to use the mesh filter in the gun or it wont let the gelcoat pass through? I removed it and looked like I had a good spray. Last question, I shouldn't be overly concerned with overspray, since I'm going to sand it later?

 

[Scott Danforth]

skip the wax
use duratec gloss additive
use a vaper gun with a 2.3 tip

mix 1:1 duratec and gel, mix with 1.5% mekp. no more..... no less. stir like crazy

spray

then immediately clean the gun

 

[jbcurt00]

AND use metric measurements.

100ml of resin and 1.5ml of mekp

200ml resin & 3ml of mekp

Much simpler and easier to be accurate, esp when adjusting the cure rate by adjusting the mekp %, even minutely.

To re-coat what you just sprayed, you'll have to sand the cured gel because of the wax.....

At 60-75*F, your right at the limit of what I'd use 1.5%. Woodonglass might have some helpful tips.

 

[dlogvine]

What about the colorant? I looked at the swim platform I gelcoated, it is still wet and sticky on touch. But there is still no color, it is clear. will try to shake up the container much harder tomorrow.

 

[Scott Danforth]

I get my gel pre-colored to an exact spec

 

[dlogvine]

almost 3 days from the first application. Some parts where gelcoat was sprayed thicker were still sticky and did not completely hardened. I think it is the temperature in 60s and in upper 30's lower 40s at night that prevents gelcoat from hardening. Bought a gallon of no wax gelcoat, since removing the wax layer from the not hardened gelcoat is not the most pleasant thing. Will wait for it to arrive, hopefully temperatures will go up a little and then will try to use 1/2 gelcoat 1/2 gloss additive and see how that will work. So far I tested it only on the swim platform, once I get the desired results will continue on the boat itself.
One question, if I have a bunch of hairline fractures on the gelcoat, what is the best way to cover them up? Should I use Dremel and go carve each crack and than patch it by hand with gelcoat and then sand and sand and sand, or can I just spray over?