To brush or spray gelcoat?

[hardguy007]

Hi,

Considering starting to spray gelcoat but have a few questions. Gun im looking at is the G100 cup gun for its price and apparent easy cleaning although open to suggestions.

1. Is is worth it if I'm only applying 7-9kg at a time?
2. Am i correct to assume that id need to rinse/clean the gun every 1-2kg?
3. Spray gelcoat is not in stock locally. Can brushing gelcoat be thinned and if so whats the best thinner & ratios? Would thinning have any effect on the shelf life?
4. Is 2 coats still required?

From what ive watched/read/discussed brushing is the simplest method and preferred my most with alot more experience than me.

 

[rwatson]

"For the most part spraying is something that I usually try and sway folks away from because of the mess, cost for equipment and experience"

 

[wet feet]

I agree that it isn't ideal for all situations.It can be the lightest way to get a thin and even coat,but every surface in the workshop will become sticky.In a plastic tent it is as harmless as ordinary efforts can easily make it, but carefully brushing is less bother overall.Costs less for consumables too.

 

[waikikin]

Hi Hardguy,

The cup guns are easiest to clean, the one I have is Polycon brand, you can dunk the nozzle into a small tin of acetone and a quick stipple with a brush it's "clean", an extra rinse will make it good for storage, usually blow through with air after. They are a little wasteful, about 110 grams will hang up in the container, this if the product needs you can brush some spare into some detail or shadow areas, I'd usually have about 900 grams per M2 standing by for bigger items, the finish peely but even and consistent if lapping coats used. With the Polycon you need to walk up to the job with the gun laid back then lower and start shooting as the gun drops, reverse for stopping... otherwise gelcoat will dribble out..
A small Gelcoat "puppy" can be made from some pipe and an air blower, the pipe just is drilled or connected to the air pipe as it exits the blower, the very most simple venturi gun with the gelcoat lifting a short distance up the tube.. the cup usually just held in tandem with your spare hand, again a relatively peely finish but ok for small blow ins. Brushing and rolling work too, rollers are uneconomical on product and also not really worth cleaning either, wider brushes are worth cleaning as much less acetone required. Some 4 decades ago I worked for DOD, we manufactured submarine hatches that went through the top of casing decks, some we brushed, but much preferred to spray with a cup gun with more consistent results.

Regards from Jeff.

polyconisg http://kcmouldings.co.uk/html/polyconisg.html

 

[aaronhl]

If I am understanding your metric system that is about 20 lbs of gelcoat, potentially 3-4 gallons in my part of the world - It would very much be worth spraying that, your going to want to use paper cups, not the plastic cup the gun comes with...the paper cups hold 1 Quart...you will only need to clean the tip of the gun each time you refill a cup, your going to breeze through spraying all of that, very easy to do...not sure what the other alternative would be, i would hate to roll 4 gallons of gel coat !!

80 psi and hold on !!