At the gelcoat stage - help needed!!!

I have been restoring a boat now for nearly two years now (almost all of this on sanding - my arms are falling off) , however I am eventually at the gelcoat stage ( the entire hull is going to be re-gelcoated ) This will be my first time using gelcoat although I have done a fair amount of fibreglass and resin work. I am going to be applying the gelcoat by roller & brush as i do not have spray equipment. has anyone else gelcoated an entire hull or even a large area in this way, I would be really gratefull for any tips and advise on this matter. any advise from prep work to getting a good finish will be greatly appreciated.

Re: At the gelcoat stage - help needed!!!

I forgot to add my current plan of action (subject to change)
I have spent months on filling and fairing so to my untrained eyes I think its ready. It has been preped to a 120 grit. which my resin supplier said would be fine.
I am also applying an initial coat of gelcoat (unwaxed) by squeegy, ( this is a method referred to in oop's massive hull extension thread ) it should eliminate any minor low spots in the hull before i apply the first coat of gel. This sound like a good idea so this will be getting done tomorow. this is how I plan on doing this critical part of the resto.

1. clean entire hull thoroughly with acetone.
2. apply gelcoat by squeegy initially.
3. apply 1st coat of gel (unwaxed) by roller and brush.
4. once cured sand entire area with 120 grit to get rid of roller/brush marks.
5. clean hull again and apply 2nd coat in the same way, and sand hull again.
6. clean and apply a 3rd coat but this time waxed gelcoat (flowcoat)
7. once cured sand again, clean again and then apply the 4th and final coat.
8. once cured start sanding with 400 grit and work my way up to 1200 grit.
9. use a buffing compound to bring out the shine.

please let me know if any steps should be added or removed.

my main questions at the moment are. -

1. am i likely to get a good finish considering i am applying by brush & roller.
2. can i sand the unwaxed gelcoat ( step 4 & 5) or will the sandpaper get constantly clogged with the tacky gelcoat.
3. when sanding the top coat should i do this by hand or can i use my 5" DA.

no doubt i will have more questions later on but answers to these will let me get started. I just prefer to do it right and do it once.

cheers

Re: At the gelcoat stage - help needed!!!

Yacht Doctor is our resident Gelcoat expert but I seriously doubt he would advise you to try and roll your boat with Gelcoat. I believe it would set up before you got it on and would develop bubbles etc. Gelcoat is really meant to be sprayed on. But like I said I am NOT a Gelcoat expert. You might PM Yacht Doctor and get is input.

Re: At the gelcoat stage - help needed!!!

I dont even think you can gel a whole boat with a roller. I could be wrong but I sure would not risk the cost of gel to roll it on. Rent a compressor if you have to and get a cheap 4.5 tip gun off of ebay and spray that pup.I know one guy on here sprayed his with an electric Wagner power sprayer and pulled it off but why risk it. I have shot gel on small parts twice. First tried a 1.8 tip gun, no joy it stank. 2 nd attempt 2.5 gun better but I feel it could have done better with a bigger tip. I am no expert. Post some pics we love them.

Re: At the gelcoat stage - help needed!!!

Gel coat will not level and flow very well when you roll it, so you will need to apply several more coats so you can sand it down, which takes a good amount of time.

If you really want to roll it (not recommended), there is one thing you can do. Squeegee the first coat like planed, roll the second coat, then squeegee, then roll, then squeegee.


The problem with rolling gel coat is the very uneven surface it leaves, using the squeegee will fill the low spots left by the roller and add nothing to the high spots. This needs to be done a couple of times so there will be enough gel coat to sand on.

The final coat needs wax.

120 grit isn't really coarse enough, 80 is much better.

Re: At the gelcoat stage - help needed!!!

thanks very much for all your advise. based on the advise given, i think i'll try what ondarvr suggests. I will squeegy a coat on just now and roll on the first coat to see if i can get a feel for it. If i don't feel comfortable with it I will invest in some spray equipment. The one thing that does worry me is the fact that i will have to always apply on a wet edge, considering i wil only have about 15 - 20 minutes before it starts gelling , this will be no easy task, although I am willing to give it a try.
I was originally going to invest in a 3hp comp and large tip spray gun but it was actually my fibreglass/resin supplier that advised against this saying, that there was no need because "a good finish can be obtained from rolling and tipping" & "other boat owners have done it this way with good results" & "our gelcoat is brushing gelcoat, we do not supply sprayable gelcoat" . they have given good advise so far and a lot of boat owners swear by their expertise, but i am starting to doubt the advise given to me by them. as i said i will try the squeegy part then put down 1 coat and I will see if I feel confident using it, If not I am sure I will be back for more spray advise. I will post some photos as soon as i learn how to, wont be long.
thanks again everyone.

Re: At the gelcoat stage - help needed!!!

ok, hopefully these pics upload. these are pics of when i first got the boat and once the hull was stripped and flipped.

Re: At the gelcoat stage - help needed!!!

paint stripping process.

Re: At the gelcoat stage - help needed!!!

fairing work almost completed.

Re: At the gelcoat stage - help needed!!!

fairing work completed, then a makeshift paint booth was made, it wont stop all dust but it should stop most dust from above the rafters from falling down. the full garage has been vacumed daily for about 3 days now to allow dust to settle. unless someone with valid reason tells me not to start i will be doing so in the next hour or so, so if anyone spots a major problem please let me know.

Re: At the gelcoat stage - help needed!!!

forgot to attach these pics, they are just pics of the guide coat i sprayed, i know everyone will be asking why i sprayed it so thick, the reason is no other apart from i got carried away and wanted to see the boat with a shiny finish, i felt it gave me good indication if i was nearly finished the fairing or not. on a couple of these pics it looks as if you could go surfing on the hull with the amount of waves but these are now smooth after sanding with a 12" x 6" sanding board.

Re: At the gelcoat stage - help needed!!!

I started applying the gel coat by squeegy, all was going well untill it started to set on me after about 8 min. I think i will reduce catilyst from 2.0 to 1.5% ratio. here are a couple of pics of where i got to. it actually goes on quite thick with the squeegy while at the same time filling all the minor low spots, so it was a great idea so many thanks for that. I might just be high on acetone but i think this stuff could be applied mainly by squeegy and very minimum brush and roller work, - what do you think about this method, I'll prob realize how stupid this idea is once my high wears off. i have to go to work now but tomorrow i will sand the part that i have already done and also do the other side. I am going to work on below the waterline first to see what finish i can get before attacking the top sides.

Re: At the gelcoat stage - help needed!!!

I just noticed where you're from, most gel coat is applied with a brush there.....and the gel coat is formulated for it.

Re: At the gelcoat stage - help needed!!!

Thanks again ondarvr. You have put my mind at rest now. I wonder if that is due to the colder weather here, or if it is just the method of choice. But after the advise given here I spoke to my supplier about sprayable gelcoat and after an extensive search he said he can get me some if needed, so if im not happy with the results doing it by brush & roller i will just invest in spray equipment and spray it on.

I overslept today so i'll probably not get much done, but I should at least be able to finish below the waterline. I will keep posting pics of my progress, so more pics later.

Re: At the gelcoat stage - help needed!!!

Well this is far from easy, applying the gel by squeegy is easy enough if i work fast before it starts to gel. my problem is sanding this stuff, its a nightmare. I tried sanding the side i done yesterday with 120 grit (hand sanding with a block) and the sand paper would almost just stick to the surface once i started. I think i may have to lower the grit to about 60 and use a power sander, i did'nt really want to do this as i don't want to undo all the fairing i have done, but it looks as if this may be the only option. anyone know of a better way to sand this unwaxed stuff? will scrubbing the hull with acetone help reduce the tackiness?
I will leave it untill tomorrow at least just in case the gel needs more time to cure, but i honestly think it has cured properly. Any advise will be really appreciated.
here is a couple of pics of the other side gelcoated by squeegy and as you will see I have to sand a fair amount off before I can carry on with any brush or roller work.

Re: At the gelcoat stage - help needed!!!

About 25 years ago I use to build fiberglass bathtubs...and a couple fiberglass boats from scratch made the molds etc for both items then the product . Now and again we would get a bad tub wall...someone sprayed the gelcoat to thick etc causes problems. I myself am getting into fixing up the bottom of my boat after an incident in the water and problems I seen before I bought it that I could fix. I don't know about the products out there today...but back when i was doing it on a daily bases are biggest problem was to get the gelcoat to cure properly on a fix. It was suppose to be sprayed on a mold then covered by chopped glass mixed with resin to seal out any air. I was told that gelcoat really never 100% cures unless it was cured with no air. So maybe this is why the gelcoat it sticky. If i had to fix a spot on the bathrub wall because of an air bubble I would clean it out and fill it with gelcoat then take a piece of plastic and tape it down over the fix for 24 hr anyway...then I knew the gelcoat was fully cured and started to sand, but that would be hard to completely seal your boat..but it can be done. But there is probaly an easier way to get it to cure properly and by reading Yacht Dr's stuff I am really impressed with him. Hopefully he comes up with a suggestion for you. Like i said I have not been at this stuff for 25 years so I have alot to refresh up and been doing lots of reading before i get into redoing the bottom of my boat mainly becase of multiple blisters over the years. . This is why I am thinking of painting my boat after I do the repairs instead of gelcoat. Good Luck

Re: At the gelcoat stage - help needed!!!

thanks for the info Outback Jack. I was originally thinking of painting with a two part paint, a couple of things put me off this, the boat i have purchased has been neglected for years, previous owners have even used dulux indoor paint to paint below the waterline, some people eh!! so i decided to strip every layer of paint of my hull (all 7 coats that i could count anyway) and also repair all damage and fair out the hull. after all my prep work there was a number of spots were the original gel coat was non existent due to the amount of sanding so instead of trying to repair these spots I thought it would be better to just start a fresh with a new layer of gel. another thing that put me off was the fact that 2 part paints really require spraying for a good finish, but this is not advisable for the diyer as its really toxic stuff and should only be applied this way in a dedicated enviroment.

The reason my first coat of gel is so hard to sand is because it is unwaxed and as you correctly state, this will not cure to 100% because of air getting to the surface, it should however be 100% cured below the tacky / uncured surface, so it is just a matter of sanding this off (easier said than done)
on the final 2 coats i will be applying there will be a wax additive in the gel coat, to my understanding this wax additive will rise to the surface of the gelcoat once applied and will seal the surface from air getting in, so these top coats will cure 100%.
The benefit of using unwaxed gelcoat for the first two coats is no sanding should be required between coats because the next coat will bond to the tacky surface left by the previous coat. but in my situation i have to knock down high spots left by the squeegy / roller & brush.
Thanks again for the info and hopefully your next project goes smoothly.

Re: At the gelcoat stage - help needed!!!

well i could'nt resist trying what I previously wrote - scrubbing with acetone , sanding with da sander (60 grit) then scrub with acetone again, I only worked on a small area just to try this and i think with a bit more work doing it this way i will get there. I'm just waiting on more hook & loop 60g discs getting delivered to me. but here is a couple of pics of the part i tried this on, it is quite hard to see from the pics but it is a big difference. so hopefully another day or two of sanding will be enough preperation for my first main coat of gel. fingers crossed.

P.S. the second pic shows were the sanding disc stuck to the tacky gel so much that it got seperated from the rest of the disc when i pulled the sander off of the surface.

Re: At the gelcoat stage - help needed!!!

hi bud........couple of things here...

first of all......if ondarvr disclames any thing i say.....follow his advice, as he has forgotten more about gellcoat than i will ever learn

the reason the gellcoat is sticky is because of the lack of wax in the gellcoat.
it will allways be sticky with out wax.
you might try to spray some pva over the rolled surface soon after a slight tack is acheived. (even a hand sprayer and hope it does not get clogged by the wax)

as ondarvr mentioned that most stuff in the uk is rolled....( i dont know why they roll it over there) the gellcoat will be thicker than the standard sprayed stuff.

since gellcoat does not lay down like paint, this will cause you problems even using the squeegee, as uneven hand/arm pressures will make ridges and high and low spots.

this is a real pain when sanding, as to make it even you may burn thru.
even brushing over a small area for crack repair takes a huge amount of sanding and usually the lows are at substraight level so a second or third application is usually nessary for a good repair.
did i mention there is lots of sanding to this process?

spraying gellcoat is really the best way to do it IMHO.

IF YOU CAN.... a standard hvlp with the biggest tip you can find will work just great. open 'er up wide and let 'er rip (dont worry too much about getting all uniform and perfectly even as you will be sanding lots off. just keep moving at a constant pace)
expect to use 3 1/2-4 gallons on a craft that size.

if you do spray...use wax. and try to get a product called patch aid to thin the gell coat.....mix the patch aid at 10% no more.
if you cant....acetone will work....but again...NO more than 10% or you mill mess with the properties of the gellcoat.

after the gellcoat is fully cured, wipe with acetone this will remove some of the wax that has come to the surface and make sand paper loading a little less troublesome

the fast gell time at 2% may be due to the products age.....the older...the faster

well.....i have to get sanding on the big regal im on now........the rain has stopped.....so its back to 600 grit gellcoat sanding....and sanding.....and sanding...lol....did i mention sanding?

HEY ONDARVR !
how ya doin bud ? wanna buy a cheap 38 fountain with staggered twins cheep?..........lol
whats up with the UK rolling the stuff? any ideas why?....is it a different mix of gellcoat?
why have they re invented the wheel?

Re: At the gelcoat stage - help needed!!!

morebass 17 said:

thanks for the info Outback Jack. I was originally thinking of painting with a two part paint, a couple of things put me off this, the boat i have purchased has been neglected for years, previous owners have even used dulux indoor paint to paint below the waterline, some people eh!! so i decided to strip every layer of paint of my hull (all 7 coats that i could count anyway) and also repair all damage and fair out the hull. after all my prep work there was a number of spots were the original gel coat was non existent due to the amount of sanding so instead of trying to repair these spots I thought it would be better to just start a fresh with a new layer of gel. another thing that put me off was the fact that 2 part paints really require spraying for a good finish, but this is not advisable for the diyer as its really toxic stuff and should only be applied this way in a dedicated enviroment.

The reason my first coat of gel is so hard to sand is because it is unwaxed and as you correctly state, this will not cure to 100% because of air getting to the surface, it should however be 100% cured below the tacky / uncured surface, so it is just a matter of sanding this off (easier said than done)
on the final 2 coats i will be applying there will be a wax additive in the gel coat, to my understanding this wax additive will rise to the surface of the gelcoat once applied and will seal the surface from air getting in, so these top coats will cure 100%.
The benefit of using unwaxed gelcoat for the first two coats is no sanding should be required between coats because the next coat will bond to the tacky surface left by the previous coat. but in my situation i have to knock down high spots left by the squeegy / roller & brush.
Thanks again for the info and hopefully your next project goes smoothly.

Click to expand...

Thanks for the info , Like i said i have been away form this for 25 years and good to know there is a gelcoat product that has wax in it to seal the gelcoat... very good idea..by your picture I am impressed with how the gelcoat went on for using a squeegie.. I plan on putting mine at the marina in the water for 3 months this summer so I am planning on doing a barrier coat myself with epoxies and brushing on a coat of paint or 2..then after i get it on the trailer i will clean it up and take it to someone to spray above the water line for me...I am not concerned to much about under the water,as It will be getting drigged up on the beach now and again...I am following alot of projects on here...good luck