Dump gun set up gelcoat

Waterman002

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Aug 21, 2021
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Hey gang! I was going through an old post about spraying gelcoat. Didnt get any tips on set up. Im doing a whole boat 24 skippy. I just sprayed the transom with a hplv gun and it wasnt a success the gun is in the trash. Bought a dump gun and set to 80psi with a number 5 and 6 tip. The results where not good. It sprayed wavy and was shooting very inconsistent( splatter). Needs to be sanded and re done. Would you guys help me with the details of compressor set up and gun set up please. I have a harbor freight 29 gal 150psi compressor connected to a 50 gal holding tank giving me plenty of air.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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to get consistent spray, I needed to add the Duragloss 904 additive

I used this gun. https://www.amazon.com/Vaper-HVLP-Spray-Gun-Plastic/dp/B000BTJALA/
(same gun my local fiberglass retailer has for double the cost)

set at 45 psi at the gun

you still need to sand and polish, however it came out more like paint

did you practice? I went thru about 2 quarts practicing with mix and pressure and gun settings before i started spraying on the boat.
 

Waterman002

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Aug 21, 2021
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I didnt practice because i set up best i could with the info i found and just hoped for the best. Gel is expensive so i just went for it. But if you have experience with a dump gun id love to hear how it was set up.
 

76SeaRay

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Although I haven't used it yet, I went with the gun that Scott recommended and will be using Duratec. My experience with painting with HVLP guns is that you get much better control with them than other types. One of the keys is the nozzle size with the gun Scott refers to providing a 2.3mm nozzle. Cheap Harbor Freight guns only go up to about 1.8mm. Clean the gun frequently, I even do that with paint. I have to do my entire boat from the rub rail up and since it is a hard top I will be able to start with it (about 25 square feet) to "practice". That way if I screw it up it will be on the very top and not really visible to most people.
 

Waterman002

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Although I haven't used it yet, I went with the gun that Scott recommended and will be using Duratec. My experience with painting with HVLP guns is that you get much better control with them than other types. One of the keys is the nozzle size with the gun Scott refers to providing a 2.3mm nozzle. Cheap Harbor Freight guns only go up to about 1.8mm. Clean the gun frequently, I even do that with paint. I have to do my entire boat from the rub rail up and since it is a hard top I will be able to start with it (about 25 square feet) to "practice". That way if I screw it up it will be on the very top and not really visible to most people.
I am using a dump gun as im doing large surfaces. Who here has experience with a DUMP GUN?
 

Scott Danforth

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cant get much larger than a 26 foot boat

dump guns are finicky and you have to have experience with them to get them dialed in. temperature and humidity are two things that effect settings.

you most likely will need the duratec additive. and yes, while gel is expensive at $20 a quart, its less expensive to practice and get it dialed in vs trying to spray and hope for the best?

you do have to thin to spray. and the duratec additive doesnt have adverse effects like thinning with acetone does. thinning with styrene is an iffy thing too.
 

Waterman002

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Aug 21, 2021
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cant get much larger than a 26 foot boat

dump guns are finicky and you have to have experience with them to get them dialed in. temperature and humidity are two things that effect settings.

you most likely will need the duratec additive. and yes, while gel is expensive at $20 a quart, its less expensive to practice and get it dialed in vs trying to spray and hope for the best?

you do have to thin to spray. and the duratec additive doesnt have adverse effects like thinning with acetone does. thinning with styrene is an iffy thing too.
Even with the big tips on a dump gun . Still have to thin?
 

Scott Danforth

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Even with the big tips on a dump gun . Still have to thin?
yes

think of trying to spray pudding. that is what gel is.

to get it to spray, you have to thin it to at least the consistency of store bought gravy
 

Lectro88

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Even with the big tips on a dump gun . Still have to thin?
Pretty sure you are going to have to thin.

I will tell you what I Can. I'm having to learn my way too.
I have done painting.., years ago, but not gel.
And I researched(a LOT) and read and talked to several buddies that paint and to others that do gel.
But I am also not going to sugar coat this as in you may not like everything I say.

You said you have hplv...
What I bought was HVLP and I have 4.8mm & purchased extra 3.5mm just in case... And pretty sure I will have to thin.(with those gigantic tips)
1st. off you might as well figure on a Lot of sanding and polishing even if you have a perfect spray.. Thats just Gelcoat. it doesn't spray anything like paint. you can just forget a smooth slick finish with gel out of the gun without shooting in a mold. And you are not doing a mold.
Again sanding, A Lot.., then polishing or clear coat over.
You have to spray it thick enough not only to cure but allow for all the sanding to get it smooth.

Every gun sprays different, everybody sprays different, even most gels will spray different from brand to brand, and things change too from what you thin with and how much you thin. THEN.. you have temperature and humidity like others have already said. Not to mention if you start spraying outside in the shade and then the sun hits it directly. and if the sun hits it you probably won't outrun that.
And you should be running some sort of air dryer if you haven't heard or know that already.
Another thing, are you running waxed or unwaxed. And you have to spray and get it thick enough to cure properly and getting the mekp ratio is another key and adding enough to overcome whatever additives you add and again Temp.
There is a lot to this and getting things to halfway turn out takes effort and a little luck helps.
And if you don't have at least 5Hp compressor, you may have air problems to boot. not enough air flow, And thats a whole different cascade of problems. Compounded with you trying to learn you'r way.
I will be running (2) twin tank compressors totaling 13.5Hp with an additional tank. just for reference, I don't want air problems. Air is 1 thing I CAN maintain control of.

1 Thing I can tell you for sure.. you need to flush gun with acetone between coats, If it ever starts kicking off in gun you probably can throw Another gun in the trash.
That has been repeated to me several times.. by many sources.

I plan to practice with at least 1/2 gallon, no way I am starting on my boat with just blindly trying to get it right by chance.
And if you think gel is expensive, and you bought cheapest thing you could find you have that as an added possible problem too.
You could always hire it done if it's too expensive.
If you continue on your boat, you are probably going to have a nice big mess.
With all the seemingly bad things I said. its just blunt truth.
I hope you find something different to practice on.
Get your gun dialed in..
Get to where you can make a good consistent pattern and blend.,. thats on flat and in corners and around edges.
Then your confidence should tell you if you'r ready for the boat.
best of luck.
 
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Waterman002

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Aug 21, 2021
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Thanks for the response. I have a dumpgun not hplv. The hplv died! Im here at the bpat and knocking it down and it seems it cured properly. I used unwaxed and the added wax on my last spray. Im thinking i just need to order more sanders and get some beer for the boys. Its sanding out nice. Might just have to spray it on ugly and spend the time to sand! Again thanks for advive. If you have anything else for a dumpgun let me know
 

Lectro88

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I guess my gun is a dump also, (canister on top 1 liter)not used it yet.
And there are several versions high & low pressure, And high & low volume.
My point in everything I posted.
First off its a learning curve to spray gel. and yes it kinda splatters like paint ball gun,. being exaggerative...
You need to get all the mixing right and thats a big deal. then everything else..
Let it cure completely..
And lastly its a lot of sanding.
So,. it's ALL very labor intensive.. every way you turn, it's a chore.
Thats why you can spend $5K-$15K hiring it done.
Sounds like you are on the right track.
But theres nothing like doing it yourself and being happy with the outcome.
And beer is cheap. -- or I hope so.
 

Waterman002

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Aug 21, 2021
Messages
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Thanks for the response. I have a dumpgun not hplv. The hplv died! Im here at the bpat and knocking it down and it seems it cured properly. I used unwaxed and the added wax on my last spray. Im thinking i just need to order more sanders and get some beer for the boys. Its sanding out nice. Might just have to spray it on ugly and spend the time to sand! Again thanks for advive. If you have anything else for a dumpgun let me know
 

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Waterman002

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Aug 21, 2021
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My gun is the cupgun dumpgun g100. It splaters it on there ugly but i guess there is no way around the excessive sanding. Im going to test different psi and tips tpday
 

Scott Danforth

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Get the duratec additive, it sprays almost like paint
 

Lectro88

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Quote;
Scott Danforth
Get the duratec additive, it sprays almost like paint

Scott.
Don't you only use duratec in unwaxed.
Or have you used in both with good success.

I have heard and read good things about duratec but I'm using waxed and it didn't even cross my mind.(as I have been told no with wax)
There is so much back and forth, like,.use or don't use acetone, use or don't use styrene, same with duratec, and many other additives and quirks.
it's almost Unless you done it for years or you get someone that really knows you are kinda driving blind.

Scott has been around a long time and I trust his advise.
Thanks for chiming in Scott.
Everything I have told him so far is from my month or more of researching, reading and utubeing. like I said earlier, I have not sprayed gel yet.
Thanks
 

Scott Danforth

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I used it unwaxed

I also called Jodi (ondarvr) since he works with the stuff all the time when I sprayed my boat
 
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