Gel-coat question

[BenKeith]

I know this has nothing to do with performance but several of ya'll seem to really know you stuff so I felt this was a good place to ask. Besides, a shiny boat with a big motor looks like it will go faster.

I want to sand and recoat the clear gel-coat on my Stratos bass boat. It's getting thin in several places and starting to look dingey. I've worked with glass but never used gelcoat. I have a Sharp model 75 siphon feed and a Sharp model 775 pressure feed gun with 2qt can. Will either of these work for spraying clear gel-coat. I feel sure the 75 won't work if the stuff is thick but hoping the 775 will. Or does it take a special contraption to spray this stuff. I've sprayed a number of cars and pretty good with a spray gun. Are there any secrets to spraying this stuff, like does it sag easily, and how long between coats.

Next, where is a good place to get clear gel-coat

[84exciter]

screw the gelcoat,paint is alot easier.did my checkmate for under $200.1000 grit wet,wipe down good and spray.next day put everything back on.done

[dan]

I have sprayed gelcoat with a pressure pot. Your gun has a fluid needle and tip sized for paint, probably a 1.4 or 1.5, look on the end cap tip. You'll have to get the fluid needle and cap sized for gelcoat. The gun manufacturer or whoever can supply you with parts can tell you what size will work in your gun. Practice on some plywood to get the pressure and spray pattern worked out. It will go on thick with a lot of orange peel. You will need to block sand it buff it and final polish it. Painting is easier because you end up with a flatter finish that requires less time to sand, buff and polish. For paint I'd use Transtar 3.5 VOC the best they make. It's 54% solids and very resistant to yellowing. Three coats should be 15 mils thick and cures hard pretty fast, if you can put it in the sun probably three or four days. Wet sand it with 2000 buff and polish after 12-16 hours or before you put it in the sun.

[all8up]

I would just use a good automitive type clear coat like dupont V7500, 2 or 3 coats would be plenty. which would give you several more years of trouble free use. You could also tint the clear, to help bring back the original color if necessary. Forget the buffing, I would try to keep that to a minimum. If you get the clear layed out right, you won't need to buff it at all.

[BarryStrawn]

Keith - Sharpe has a pretty good website and message board. I'd bet Dr. Gun can help you figure out your options.

http://www.sharpe1.com/cgi-bin/ubb/Ultimate.cgi?action=intro

[TTriton]

it can be a pain in the butt to sparay and you won't get the gloss you want with out additives. I prefer a quality paint. It is much easyer to spray and to work with. If you do spray gelcoat there is a additive that works fairly well but I forgot the name of it. Even with the additive it still took a good bit of buffing to get the gloss that my customer wanted.

[Scream And Fly]

Ben,

I could be wrong, but I'm willing to bet that your hull has automotive clearcoat on it from the factory. You might want to double-check with the factory...

Greg

[BenKeith]

Hey, I'm easily convenced. I was not looking forward to having to deal with that stuff anyway. I just didn't know a good clear coat would hold up.

There's no way I'm gonna mess with gel-coat since a good clear will work

Thanks a bunch.

[TTriton]

good luck with the job..

If it is clear coat gel, all you have to do is scuff it up and put clear gel right over it, spray it, hell you can use a paint brush.

All the scratches will disappear.

If your putting clear on gel, that clear IS GEL and it is very easy to add coverage.

Usepaint on paint, gel on gel.

[FCnLa]

I usually have it on my toast!:D

Mold yes, top coat, NO!!! Unless you use Patch Aid (wax solution and resin) and that is not feasable. Way too much work.

Your boat is probably gel, but like Greg said, check with your manufacture.

If your stuck on a gel type (polyester based), there is a good product called Duratech. Most fiberglass suppliers have or can get this. It is availiable in clear and they also make a primer. It lays down well and responds to buffing well also. Automotive paints are OK, but I would rather boat paint made for boats. AwlGrip, by US Paints is my choice.

Good luck!:)

[Liqui-Fly]

You'd better be very careful sanding or else you'll wind up with a silver boat. David

[Raceman]

I bought a used brown/gold Vector one time and the clearcoat was dead flat and so bleached it felt like sandpaper. A local paint shop sprayed it with clear Imron and it looked like new. Some other people on this board have had good results with other products, but the Imron, although thought to be obsolete technology is excellent on a boat and I've never seen a weekness in it unless it's the danger in being exposed to it during application. One word of caution about gel coat. Some gel coats will never set up properly when exposed to air. These types are the ones that are generally sprayed in molds. I understand there are some spray on coats that can be put on top of them, facilitating hardening, and also some gels of a different type that will air dry, but the point is, if you decide on gel, talk to someone who really knows the characteristics of the product.

[AlaskaStreamin]

I just sprayed three hulls and a deck lastnight with gelcoat. I'm using a Binks #7 siphon feed with a .064 needle. I use this gun for everything, primers, base coats, clear coats, and gel coat.
Here are a few tricks.

I keep the gelcoat warm (around 75*) get it too warm and you'll be buying a new spray gun.

I use Styrene to thin the gelcoat not acetone. (10% max.)

The stuff is pretty thick but it does spray nice. I crank up the pressure to around 65-70 psi and go for it. Two drops of Cobalt in each quart really kicks it and I can be sanding in an hour.

I don't add surfacing agent to the gel coat (wax), but spray PVA (Poly Vinyl Alcohol) over the top when I'm done. I seem to get a smoother surface this way.

Gel coat is $35.00/gal and Interlux Yacht paint (catalized) is $48.00/qt. I wetsand and polish all my spray jobs so it comes down to price for me.

Good luck on whichever way you go!

[Liqui-Fly]

How do you know when it's time to spray the PVA over the top. I experimented with Gel Coat for the first time and never reallycame up with a good formula. The temps were low in my garage too. I tried almost everything including dissolving parafin in my styrene. This is supposed to coat the surface as the gel dries underneath. David

[AlaskaStreamin]

I spray the PVA as soon as I'm done cleaning out the gun. Usually the gelcoat is getting "stiff" by this time. (about 15 minutes).

[Liqui-Fly]

It would seem like chemistry of the system would allow it to cure properly at a broader range of temperatures but it seems to be very fickle. Have you had success at most temps or is a warm shop a must?

David

[AlaskaStreamin]

I believe temp has a BIG factor. Adding DMA and Cobalt really speeds up the gel and the gel to cure times. I would think in colder temps you would want to use these additives. I do crank up the heat after I'm done spraying and am sure this helps. Also getting fresh products plays a factor. Some of the pre packaged resin and gelcoats are pretty low quality and you don't know how long they have been sitting on the shelfs.

[Liqui-Fly]

Polyesterification is an equilibrium reaction in which water must be continuously removed. So in order to make a good coating (high molecular weight polymer chains) then water must removed or else the cure cycle will stop. I'm thinking about messing with some physical drying agents that will form neutral species after aiding in the cure. This might help where a warm gargage isn't available.

David

[AlaskaStreamin]

David,

You don't want to add any foreign chemicals to the gelcoat (ie: jap drier) to dry it.It will interfere with the molecular chain reaction. Humidity above all else will slow the drying process.

Moisture getting in the gelcoat produces polystyrene which is the gummy coating that gets on the surface.

By adding Cobalt (chemical name is Co-Nap), you'll increase the cure time thus giving the humidity moisture less time to produce the polystyrene. Cobalt is found in resin products and it is acceptable to increase this amount (not to exceed 8 drops per quart) Caution: DO NOT ADD CATYLIST DIRECTLY WITH COBALT!!!! Thoroughly mix in the Cobalt BEFORE adding the catylist.

DMA and DMAA are other additives. Unfortunately these aren't sold over the counter as far as I know.

The temp. will still be a hinderance (below 50*). Look for a portable heat source such as a space heater to get the temp up a bit. Hope I've helped a little.

[dan]

here's a source for gelcoat and other supplies:

http://johnrsweet.com/Resins.html

has some useful tips

[Liqui-Fly]

That DMA may be what I was thinking of. I wasn't thinking of a solvent type deal like jap drier. Is DMA - Dimethyl Amine - if not do you know what it is? Over the counter isn't important. This is cool cuase I wanted to do a couple small projects this winter but I'm goping to have to do them at lower temps. Another note to anyone that might be following this...never heat your projects with gas type heaters (propane ect) because water is given off as a byproduct of the burned fuel.
David

[AlaskaStreamin]

Hey Dave,

Yep, you got it. DMA is actually Dimethylene Amine. Two drops and you're DEAD!!!!!! Mega bad stuff!! I have to get my supply from our local boat builder. I get a lecture each time I fill up my eye dropper. (I have three kids). I keep it high up on a shelf and have a skull and cross bones on the label.

DMA is mainly for Ortho resins and the DMAA is for the Iso & vinylester resins and gelcoat. I forgot what the extra "A" is for.

Fun thread!

:)

p.s. A neat trick on small projects is to use a heat lamp to warm up the repair area. The stuff should set up in fifteen minutes. If you're going to shape it afterwards, put a piece of wax paper over it and smooth out with a bondo spreader. Leave the wax paper on till it cures. Makes sanding a breeze!! No gumming!

[BenKeith]

Ya'll are usimg up all my printer paper. I keep printing these post out for reference, each time it has to print all of them.

I've definitly gotten some good advice and info. I've called Startos to see what my clear coat is but they didn't return my call. Tried the Stratos owners web sit, to no avail. Stratosboats.com is up and running now so I emailed them to see if they will answer my question that way.

Anyway, if it is Gel-coat, after reading the post, I guess I should go back with Gel-coat. Kinda hopeing it's not now.

I emailed Sharpe (again some more great info ya'll gave me) and they gave me a list of part numbers and recommended I convert my model 75 to the pressure pot and gave me the numbers for the fluid tip, needle and air cap they recommended for gel-coat.

AlaskaStreamin,

If it turns out to be gel, hopefully should know in a couple of days, might need some more help. You say you spray with your Binks shiphon feed. I'm much more comfortable with a siphon feed. The only thing I've ever spayed with my pressure feed is the kitchen cabinets. Do you think my Sharpe 75 will work in siphon or should I go on Sharpe's recommendation and use the pressure pot?

I see Gel is creating another problem for me. Looks like it's going to take a lot more air to spray it. My little 2 hp single stage electric compressor just will keep up with automotive paints and 60 psi at the gun. My big compressor is a two stage 26 CFM unit but it's gas powered so the compressor head runs all the time, heating up quickly and with heat comes moisture. Don't sound like this stuff likes moisture at all. Anybody got a good home remendy for catching moisture before it gets to the gun. Can't afford a refrigirant drier just to spray one boat.

Thanks everybody for the great info.

[FCnLa]

You can use gel coat, Duratech, or any of the other paints mentioned here. That is your choice. I believe the aircraft or boat paints would last the longest. They will require less maintenance. I painted my boat with aircraft paint and have not waxed it or anything for seven years. Looks just as good as it did as the day I painted it, which is not real good I was in a hurry:o and plan to redo it this winter.

One thing about pressure I have learned about recently. Always use recomended pressure. If you do not, it may leave small pin holes that cannot be detected with the naked eye. These holes will trap water. This seems to be a cause of water blisters on the hulls of gel and painted boats (mine did it). You have to use enough pressure to fully atomize the paint so there is a smooth, uniform surface.

As far as a water separator, I have a redneck/hillbilly version.

Take a piece of pipe, (pvc will work as long as it is schedule, I think, 40 or better, at least 250 psi) This will be standing on end. Mine was about 3 ft tall. At the top is a elbow that will be the outlet for the hose. One foot off of the bottom I put in a "T". This is the air inlet. At the bottom I used a fitting converting to threads again. I install a valve ( I like metal ball valves). The air will go up the pipe and the water will fall down into the trap.
Of course you can play with pipe sizes. The bigger the better with in $ reason. Height can be changed too.

When I am painting and the moisture is high, I will crack the drain on the compressor and or the trap.

[ProComp]

Any recommendations for prepping a boat prior to putting on a coat of Imron clear? Thanks.

[dan]

here's some general clear prep steps. wash the surface with soap and water to remove wax and dirt Dawn dish soap is a good wax stipper. remove all hardware and tape the screws thru the piece as you take it off. move outside if possible to sand. use a dust mask. dry sand with a da and 800 grit or hand sand with 1000, use a 3m grey scuff pad(about 800) to get areas you can't sand. really sand well, this is what will cut down on first coat runs and give you the bond you need. take a break. wipe off the area you sanded look for any reflectivity and now really sand it. blow it off with air while wiping with a grey scuff pad. wipe down with a wax&grease remover PPG makes one. move into your painting area. cover anything else in there you don't want over spray on with light plastic drop cloth. run a line of 3/4" 3m tape along the border separating the non paint surface out. cover the areas of the boat not being painted with plastic drop cloth and tape its edge to the 3/4" tape line with 1-1/2" cheap tape. use masking paper on smaller areas. don't cut with a razor blade on the boat surface, cut with a new blade just above the surface.

this will probably take a whole day, so plan on painting after a good rest. get lights and borrow some more. don't wear anything you had on when you were sanding. use a short sleeve tee shirt and paint hat. get a chemical rated mask. use a tack cloth to wipe down the surface. mix two quart cups of clear for your first section, mix two more when these are gone, load one in gun. use enough air pressure to flatten the clear as it goes on. test on a big piece of cardboard until you are correctly adjusted. start on the top. do not start painting until the area you are going to coat is lined up with a light so that you can see a reflection of the light on the surface. you can't judge how thick you are putting the paint on without that reflection, so do a dry run over the whole length making sure you see a reflection. if not move some lights. as you spray an even coat perpendicular from the surface watch the reflection of the paint going on. if it looks grainy it's going on too light or you are over spraying an area. the top should be pretty easy, the sides will have a tendency to run. put a light coat on the sides and let it flash off for twenty minutes to give you a good base for the future coats. if it starts to run let it flash without putting more paint on, you can wet sand runs later. avoid trying to cover over them with more clear when they're wet, you'll just have more to sand later. after the first flash recoat a good coat watch the reflection. let it flash and recoat. you will have dirt, if you let a coat flash enough you can remove some before the next coat with a tack cloth. without an exhaust fan a lot of paint will be floating around and will settle on the top surface. you can sand and buff later. three coats should give you a thick finish. let it cure at least the recommended time. wet sand dirt spots and runs lightly with 800 and a lot of water followed by aggressive rubbing with 2000 and water in a continuous small stream from a quart squirt bottle. use a rubber sanding block or pad. listen to the sound of the sandpaper, if you start to get a higher pitched sound you're pushing a dirt particle into the finish and scratching it flush with water. you want to wet sand with 2000 until the orange peel dimples are almost completely gone with an electric buffer and a wool pad use 3m rubbing compound on a dry surface to get the first level of gloss. if water is present the pad will gum up and the job will take longer. use small amounts of rubbing compound and pulse the trigger to load the pad or smear the compound over the surface before you start buffing to limit flinging the stuff everywhere but it will still get all over you. every few minutes clean the wollpad surface by spinning it as you drag the tip of a screwdriver or large bolt back and forth to get the dried compond off. now as you go along you will find areas you haven't sanded as flat as you thought or dirt bumps you haven't removed. wet sand with 800 and then 2000(a lot) and dry with paper towel before buffing. do the whole boat then come back with a foam pad and 3m foam pad polishing compound for the final shine

it will shine like glass. good luck.

[AlaskaStreamin]

Wow, this is getting fun!!!

David, You know, if you aren't planning on walking on your deck, the Imeron might be the easiest to apply with your current set-up. It seems like going to gelcoat is going to be a pain!
BTW, I would think if you had a .064 needle or larger, you could spray gel coat. Sorry, I'm not that "up" on spray guns.

I sprayed my dad's Glastron Carlson 9 years ago with automotive paint. I added craft glitter to the clear coat to give it the metal flake look. We climb on the bow with sand and grit on our shoes and it does get scuffed up. Every few years I wet sand it and run the buffer over it and the shine always comes back.

I am using a 5 hp twin cyl Puma on a 30 gal tank. I have a water seperator at the tank, one at the end of the main hose, and a little inline clear one that is threaded right on the gun. I use a 6' "whip" between the second seperator and the gun.

FCnLA's hillbilly seperator is a great idea to have hanging on the wall near where you are spraying. The closer the better.

Pro Comp,
The condition of your current gelcoat, decides what grit to start with. Usually 220 grit is sufficient. I have the luxery of having an air powered jitterbug sander with a rectangular pad. I can wet or dry sand with it. It seems like the 220 wet paper is courser than the dry paper. Either way I would finish with 320 grit. I've gotten away with 220 but finer is better. I woulden't go any finer than 600. If you wet sand by hand, I would get a soft pad to wrap your sandpaper around. These are like 3"X5" foam pads that are around 3/8" thick. I have hand sanded my fair share of boats and it doesn't take that long. Wet sanding always seems to go faster for some reason plus the dust isn't there. Oh yea, If you wet sand, add a small squirt of dish soap to the water. If you dry sand it, You will want to wash it really well or use a degreaser before sanding. This will insure you don't sand any oils into the pores of the paint. Fish eyes always SUCK! If you ever get a fish eye while painting, one trick is to let it sit 15-20 minutes and apply a dust coat over the area then wait 15-20 minutes and repeat until it's covered with the dust coats. This "bridges" over the oil spot then you can continue with your painting. Some paint manufacturers actually make fish eye eliminator. It is an oil additive you squirt in the paint so it doesn't react with the oil that is on the surface. Once you add the eliminator, you have to keep adding it to the rest of the paint you are going to be spraying. You do sacrifice a little bit of orange peel using this.

When I worked at a body shop, some of the heavy equipment we painted had so much oil impregnated in the paint, we coulden't help but to use the additive.

Ben,
Grab another ream of paper, we're not done.

:)

Thanks for starting this thread!!!

I'm going to be out of town Monday for a week so don't think I'm ignoring you guys.

[FCnLa]

Cannot disagree with any of it.

Ron, or anyone else ever use those pads,cannot remember the name, but it attaches to a DA pad via velcro. They (3M) also make a foam (real spongy) that goes inbetween the pad and sand paper (velcro too). You can get paper well over 1000 grit. The light foam evens out the weight of the pad and sander eliminating spots that are sanded too much (ridges and body lines). If you have not tried this, it is awesome. It does have start up costs, pad, foam pad and the special paper, but well worth it. No more wet feet!!!:D

Another tool of value, have used one, on my tools to buy list, one of those small DAs. I guess the pad is about 2" in diameter. Makes doing small tight work a breeze. If you try one you will have to have it.

Ron, what do think about the air pressure and small holes theory? Not mine, came from my buddy.

[AlaskaStreamin]

FCnLA,

I started to respond to the pin hole theory then deleted it as I diden't want to "speculate" BUT since you asked, this is what I've heard. This is reguarding to blisters. The blisters I see are below the waterline in the larger boats that live in the water. In the 70's some of the big resin manufacturers would make "deals" with Bayliner, Uniflite, ect. for large quanities of "hodge podge" resin that was a mixture of laminating, tooling, and other resins used as an "economy" but acceptable resin for manufacturing. They were still trying to exotherm (off gas) through the least resistance ie: the gelcoat. This is what I've heard and can't a-test to the validity.

I've seen moisture create little blisters in car paint jobs but not in gelcoat.

In an earlier post in this thread (Ben has it printed several times I'm sure. :D) I talked about moisture causing polystyrene which is the gummy jizz that sometimes gets on the surface. I'm pretty sure this is where the moisture ends up. Now air line water may have a different effect than moisture in the surrounding air. You got me! I'm still learning this stuff too.

Tools:

The 2" DA (Dual Action) sounds interesting. Never seen one!

A HD hacksaw blade (2"X12"X .080)works GREAT at removing orange peel and cleaning off the jizz (If you get any)Use the back side of the blade (Yes, it's smooth, sheez!) It doesn't clog up and you drag it across the surface on edge. You use the other side (Yes, the tooth side) on edge scraping diagonally to smooth out putty (resin and microbaloons). My mentor is making a 26'hull plug and is putting on 5 gallons of resin putty at a wack. He uses a 24" wide roller to roll out the putty then 30 minutes later attacks it with this blade. He can smooth out 1/2 the bottom and side in fifteen minutes. It's great for rough shaping.I would think any stiff piece of steel with a slight beveled edge would work for scraping gelcoat orange peel. Trust me, I've seen this work and it is amazing!

Dan,
You and I were writing at the same time. I diden't see your post till after I sent mine.

Seems like we are pretty close on the painting except for the grits. Three coats will cover 220. I would think anything over 600 would be polishing and you woulden't get a good mechanical bond. I say this because I wet sanded a mold with 1000 grit and laid up a part without buffing and waxing.(Brain fart!!) (it was a fiberglass offshore exhaust snout). The part pulled out without much resistance. What makes you like the finer grits?

[dan]

using 800{DA-1000 by hand} under clear only probably isn't necessary, you're right, three coates will cover 220 or 320 and give you a better bond. if you're adding any color with metal flaking in it to redo faded striping under the clear 800 is necessary for that area so no scratches will show up in the color. at least that's the fast way of prepping for a stripe. for a better bond sand eerything with 320, tape off for the stripe and paint the stripe with sealcoat to fill the 320 stratches then color then remove the tape and masking when everything is flashed.
800 is a hold over from auto panel painting where you are prepping an area with an existing relatively thin coat of clear over a color coat. you want to abraid the clear but not sand through to the color and damage it. you may be repairing one end of the panel with filler, primer, sealer, color and then clearing the entire panel to blend in a successful repair.
220 or 320 will save you time too but be careful to pay close attention to thin spots in the clear gel, edges and ridges if you're using a DA so you don't sand through. things go faster with coarser grit and gouging is a problem to watch going into concave areas. you can use the red 3m scuff pad(about 320) for areas you can't reach with a DA.

[BenKeith]

Ought to put this in a book.

A guy couldn't take a year of Tech School and get this much good info.