Spraying Marine Urethanes

[drewpster]

Re: Spraying Marine Urethanes

Ok good everybody made nicey nice. It is easy to misread people's posts. I'm glad we all get along.

While we are on the fairing subject, I have a couple of questions. I started my deck by stripping what looked like latex off the deck and finding most of the original gelcoat missing, damaged or crappy. I sanded it with an orbital after cleaning it and coated the entire surface with marine epoxy, silica, and balloons. I then sanded, sanded and sanded some more until I got a surface I was happy with. I then started in with a couple of different boards I borrowed from my bodyshop friend. Doing it by hand was difficult to say the least! The fairing compound was terribly hard to sand. This was my fault because I had to wait too much time between sanding missions to get it done. I am sure I let it cure too long before getting the flat boards going. I am happy with what I have and I am through (maybe) sanding the deck and ready to do the final coat. That said. what could I have used to block this deck that was aggressive enough to cut the fairing compound that was that hard?

I still have the outside of the hull to prep for paint this summer. There is one area in particular that is going to need some fairing before I proceed. (and a good bit of filling scratches and missing gelcoat) Should I go with the fairing compound I used before, or try a different one? Should I get an air file to flatten the hull?

I like my deck, but there are some waves in it. I want to do a better job on the hull. We went with a lighter color on the hull because I was afraid the dark blue my wife wanted would show to many defects along with my amateur fairing work.

 

[ondarvr]

Re: Spraying Marine Urethanes

I know everybody wants an excellent surface when they're done, but there is a characteristic of fiberglass that tends to undo some of your hard work, in that It can, and will change shape over time. Every thick or thin area will change shape at a different rate and amount, also every bulkhead, core, fillet, stringer, backing plate, etc will make, or let the area around it change shape differently.

This comes into play even more when the glass work is done in cooler temps, or the correct amount of catalyst is not used, the resin will not cure completely in a short amount of time, although it may be appear hard. Then when you paint it with a light color (paint or gel coat) in one area and a dark color in another area, the dark color gets much hotter in the sun and will change the shape of the surface much more. The type of resin used will also change how it reacts to heat and age, most hulls now have a skin coat of a better quality marine type resin behind the gel coat and the bulk of it will be made from a less costly resin. The deck might have a skin coat, but it is less common so the deck and hull may change shape much differently. Depending on the size of the boat and who made it, older boats may be made this way also. Plus boat companies change resin suppliers from time to time and each resin can act much differently to heat.

After all of that, now you put some filler on the surface that is made from a different type of resin, possibly epoxy, then you add milled fibers, ballons, or silica and you end up a surface that is much different in some areas than others. Now you spray on primers and sand again to fair the surface even more, so over the top of all these different things that make up the hull or deck, you end up with an uneven layer of some type of primer.

Sometimes all of this works well and you end up with a long lasting true surface. Other times, the first time it's in the sun and it heats up, it will change shape and you can see every one of the differences I discribed earlier. Most of the time it's someplace in between these two extremes though.

 

[Yacht Dr.]

Re: Spraying Marine Urethanes

ondarvr is right on.

puttting unequal densitys over an area will tend to expand and contract at different rates ( example.. If you put alot of putty to fair out a glass repair..that area will be a different "density" especially when using lightweight fairing compouds such as ballons.)

the best suggestion is to "post-cure" your heavily filled areas .. glass or filler. ( POST-CURE = heating the area using lamps to a temp of 130-150 deg. for 4-5 hours )

that way when you do get out into the elements the repairs wont move as much.

 

[drewpster]

Re: Spraying Marine Urethanes

My boat was built in the late sixties. The deck is laminated plywood. It appears as though the ply deck was coated with polyester resin and gelcoat. Before my time a former owner tried to refinish the deck. It looked as though they gave up trying to recoat gelcoat on the aft portion of the boat and used latex paint to cover the deck. Sanding revealed the underlying coating. I then recoated it with Mas epoxy using their mix ratios. It cured very hard and difficult to sand, but I got it smooth, its just a little wavey. Should I be concerned about movement causing delaminating? It seems very solid at this point.

 

[drewpster]

Re: Spraying Marine Urethanes

Here is were coating began

Here it is underway

Here it is after the first coat of Brightside

 

[drewpster]

Re: Spraying Marine Urethanes

Ok take it easy on me. Allot of what you will see here is bad photography. But here are some pics of the deck in decent light. (i'm beginning not to like it)

 

[Yacht Dr.]

Re: Spraying Marine Urethanes

I personally think you did a FINE job there m8..

hats off to ya !

 

[ondarvr]

Re: Spraying Marine Urethanes

What don't you like? It looks fine, it would take a lot of work to make it much better.

 

[drewpster]

Re: Spraying Marine Urethanes

Thanks to you both. But now I'm frustrated. I just tried to use my HVLP gun to shoot some Brightside. I tried it before with Pre-Kote and got nowhere. Now I have tried it with the paint. Again nowhere. The gun is a Mac Tools HVLP gravity feed with a 1.8mm tip. I have regulated filtered and dried the air to 29 lbs. I have gone through the air, fluid flow and pattern controls several times. I thinned the paint 25% using 216 thinner. Everything to my knowledge is as recommended by Interlux and the paint gun instructions. (aside from thinning, Brightside can says 10% max by volume, I tried TGunner's 25% from another post) What in filth and foul am I doing wrong here!?

 

[drewpster]

Re: Spraying Marine Urethanes

Update: I just went and reviewed Interlux's instructions on this. They list 333 thinner for spraying. (TG was correct) The can says use 216. Also none of the guns they have listed are Gravity feed guns. (Pressure pot or siphon cups only) The tip size I am using is correct. But appears I will be in the market for a new Siphon gun. Think I will go a little cheaper this time. (Geez!)

 

[Yacht Dr.]

Re: Spraying Marine Urethanes

gravity feed gun is just an inverted siphon feed..so It should work just as well if not better..

I recomend a 2 qt pressure pot from Harbor Frieght.. cheep m8

peace and GL

 

[Boomyal]

Re: Spraying Marine Urethanes

Update: I just went and reviewed Interlux's instructions on this. They list 333 thinner for spraying. (TG was correct) The can says use 216. Also none of the guns they have listed are Gravity feed guns. (Pressure pot or siphon cups only) The tip size I am using is correct. But appears I will be in the market for a new Siphon gun. Think I will go a little cheaper this time. (Geez!)

What does happen when you try to spray? Will the gun shoot straight lacquer thinner? If not, something is plugged. I had that happen once when I apparently did not clean the gun well. It wouldn't even spray lacquer thinner.

I left the LT in the cup for a while, then went back and pulled the trigger.(30 to 45 minutes) It began to work. I dumped the thinner, poured in my paint and finished my job.

I learned how to clean an HVLP gun after that episode.

ps, I just thinned my Brightsides with automotive medium reducer. It worked just fine.

 

[iwombat]

Re: Spraying Marine Urethanes

I've noticed that a lot about interlux paint. When they list thinning, primer or cleanup depending on where you look it seems they site a different product. Website, can, and printed instructions all differ from place-to-place it's all very confusing at times.

 

[drewpster]

Re: Spraying Marine Urethanes

The gun was new. I set it up per the instructions. Just before thinning a small batch of Brightside I shot about 2 oz. of Lac Thinner also per instructions. (29lbs air at gun) It came through fine, well atomized and made a good pattern.

I filtered 2oz paint into a clean pot, thinned it with 1/2 oz. of 216 thinner and mixed well. Poured the thinned paint into the gun. I started with the fluid control wide open, the air about half way and the pattern about half way. The best I could get out of the gun was a small amount of paint spatter with no pattern. Fluid control only caused less paint to come out. Air and pattern controls had no effect.

I have had the basic components of the gun apart for cleaning. The tip looked clear and I could find no obstruction in the gun anywhere. One thing I did notice is that the gun can be triggered slightly and only air will come out. The trigger must be pulled fully rearward to paint. I assumed this was normal. Weak spatter is the best I am getting out of this gun.

 

[Boomyal]

Re: Spraying Marine Urethanes

Yeah drewpster, the halfway position on the trigger is normal. At arms length I am at a loss to figger out what is wrong. If the gun sprays and atomizes thinner with a .18 nozzle it sure as heck should spray thinned Brightsides. A .18 nozzle is pretty big.

Where are you regulating the pressure? at the base of the gun or at the compressor? I've found that I need to run the compressor pressure up at 60 ish lbs and dial the regulator at the base of the gun down to 15-20 lbs.

Still, if it sprayed the thinner the way you have it, I just don't know.

What is your compressor's specs? CFM etc

 

[drewpster]

Re: Spraying Marine Urethanes

The regulator is another thing that I am looking into. I bought a cheap one that is connected at the base of the gun. I also have another one located at the compressor tank. I'm sure the one at the tank is good. Its a quality unit that I bought wit the compressor years ago. I am going to replace the one at the gun.

I'm not sure of the exact specs of my compressor. It is one of the larger horizontal tank types. I assume it is ok because I have run many air tools with it in the past without allot of excessive cycling. It has a 30 or 40 gallon tank? I have had it for years.

 

[Bert]

Re: Spraying Marine Urethanes

Guys, I see one thing that may be causing problems. One person refers to a nozzle size of .18 and another says 1.8MM. 1.8MM translates to about .070. If this is the case, mixing english and metric units, then there will be confusion and this could be the reason for spraying problems.

 

[Boomyal]

Re: Spraying Marine Urethanes

Guys, I see one thing that may be causing problems. One person refers to a nozzle size of .18 and another says 1.8MM. 1.8MM translates to about .070. If this is the case, mixing english and metric units, then there will be confusion and this could be the reason for spraying problems.

My fault for doing that but we were still talking the same thing. I said .18 and drewpster said 1.8mm. I meant the same and that does translate into .070 in, which is stated as suitable for heavy enamels and primers.

If you can hear me Drewpster, make sure that you are running full pressure at your compressor regulator, then dial it down to your 29 psi (my deVillbis states 24) at the gun regulator, [colour=red]with the trigger pulled[/colour]. Otherwise you may not be getting a high enough CFM. For my deVillbis gun, they say it requires 13 cfm with 24 psi at the gun inlet and a resulting 10 psi at the gun tip. You have to have their little guage to measure the tip pressure, which I do not have. Also I know that my compressor most likely does not deliver the 13 cfm, that's why I have to run my compressor regulator wide open at 120 psi to keep from restricting CFM down the hose. But my gun still works well, I even sprayed my sons car with it.

They also state that the hose should be at least 5/16". The longer the hose, the more CFM that is lost.

My deVillbis manual also states that some brands of gun regulator valves cut off too much cfm, where theirs does not.

 

[drewpster]

Re: Spraying Marine Urethanes

That makes me think that the regulator is the problem. I started my work week so it will be next Monday before I can try spraying again. After doing some more prep work I realized that there are some areas where spraying will be necessary in order to reach the lower portions of the windshield.

The hose I am using is a standard 3/8 shop hose. I can afford to take out a section of hose and still have enough to reach the work so I will try that also.

I cant remember who wrote (iwombat i think) mentioning the danger in spraying Interlux Perfection two part. I also remember reading something about it somewhere. I have a decent respirator but I was wondering if anyone knew what, if any special equipment I needed to spray Perfection?
The main reason for selecting Perfection is color selection. My wife and I spotted a gorgeous sportfisher in the Keys last year with a white upper half and a pale yellow hull. We both loved the way this million dollar dream boat looked. Perfection comes in a "Fighting Lady" yellow that looks just like it. Its fitting because while the style is very different in 1960, Revel Craft listed my boat as a Sportsman's Weekender back then. The 'Revelier' model.

That color works well but I do not want to spray it if I have to go into debt buying a spacesuit to do it safely. I wonder if I can mix some Brightside white into the darker Brightside yellow and pale it out to make my color?

 

[Boomyal]

Re: Spraying Marine Urethanes

All of them want decent respirators. As far as mixing the stock colors, just use precise measurements so that you can duplicate it in the future.

ps, to eliminate your inlet regulator as the problem, take it off then dial your compressor regulator up to 15 psi over the recommended inlet pressure and try it without. (assuming 25 ft of hose) Be sure to use a moisture filter at the gun.