spray painting the sides

tgalea

tgalea

Well-Known Member
Joined
29 Dec 2001
Messages
202
Location
Malta
Visit site
Hi all,

my boat sides are now in depserate need of some paint since they are all scratched and looking awfully dull.

I would like to spray paint them but require some advice with regards to what paint i should use.

Locally, the person who i'm planning on using to spray her said he'd rather use car two pack paint such as ICI autocolor. What do you think ?

Just in passing, would international's perfection 2 pack paint be sprayable at all or not ?

Anyhow what have you people used when spraying your boat ?

Thanks for your advice and regards
Tyrone Galea
 
International 2 pack is sprayable according to their literature. I would be a little careful using auto spray paints, to be sure that a) the paint thinners does not react with the gelcoat, and b) that it will actually adhere properly to GRP and will stay put.

If the topsides are scratched you will need to make good before spraying as even the slightest imperfections will stand out like a sore thumb in the new paint coat!
 
Have never personally painted a whole boat by spraying , but done frequent patch repairs.

the real problem will be getting undercover and the humidity controlled etc

have sprayed international 2 pack and lots of awlgrip with the required standard, using normal car repair grade spray equipement.

personally wouldnt use auto paints for topsides
 
Thank you for your reply.

Would you think i can just sand down the scratches, fill with something like interfill and respray on the existing paint (after sanding it down lightly), or do you think i should sand all the way down ?

Regards
Tyrone
 
Beware that the isocyanates in 2-pot polyurethane paints are very toxic. You need to use a pressure fed mask if you are going to spray it - even outside. I suggest you look into using a foam roller and tipping off with a foam "jenny brush". Do a google search on "roll and tip". I used this method with international 709 and you cannot tell the difference from spraying - almost mirror finnish, but this depend on how thorough the surface preparation is. Use an random orbit sander with 120 discs.
 
The danger with sanding all the way down is that you could easily go right through the gelcoat. Better to use a filler to start with, and loads of rubbing down to get a decent finish. Filler must be compatible with whichever paint system you choose. A useful dodge for levelling is to apply an undercoat of a different colour, then you know when you have rubbed right through. if you are building up paint layers, alternate the colours, so that you know when to stop rubbing down.

Preparation really is the key to success, the more time you spend flatting off, the better the finish will be. Before final finishing, rubbing down with 800 or even 1200 grade will give a far superior finish. 120 grade will remove plenty of material, but is far too coarse for a really decent finish. Ask any paint sprayer!
 
i would personally use any 2 pack as long as it had "Awlgrip Polyurethane " on the tin.
no others come close to Awlgrip
so to re-cap Awlgrip or Awlgrip /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
 
[ QUOTE ]
International 2 pack is sprayable according to their literature. I would be a little careful using auto spray paints, to be sure that a) the paint thinners does not react with the gelcoat, and b) that it will actually adhere properly to GRP and will stay put.

2k thinners wont damage the gel its not really strong enough to unless continiously left on or really rubed with a rag,
whereas cellulose thinners will melt the gel.
 
I really couldn't recommend using auto paints on hulls in a marine environment. Snowleopard might have a view on this! However if you do do it and it lasts more than a season I would be happy to hear about it as it might make me quite alot of money!
 
I have used automotive 2-pack acrylic on boats with very good results, the finish is very hard and if you think of the abuse, sun , salt etc, that cars endure and still look good, it should last well on a boat. I use an etch primer first on the prepared gelcoat, this ensures good adhesion and then do any filling on top of that. Next, if needed, a coat of high-build primer to fill small scratches and then 4 coats of topcoat, applied wet-on-wet. With good preparation, the finish will be as good as the original gelcoat and last many years. The cost of automotive paints are less than marine if bought at a trade suppliers (they all sell to the public anyway). Wear an organic vapours mask when using 2-pack paints and so long as the temperature is above about 12 degrees C the paint will cure ok ( I have painted outside in March with good results).
Peter
 
thinners wont damage the gel its not really strong enough to unless continiously left on or really rubed with a rag,
whereas cellulose thinners will melt the gel.

[/ QUOTE ]

... but the thinners are in the paint, so will remain in contact with the gel coat until they have evaporated off, so care IS required that the specific paint in use will not damage or soften the gelcoat in any way. Many thinners are perfectly OK - otherwise it would not be possible to paint GRP, but others most certainly will attack the resins, so you need to be sure the paint selected is not one of these.
 
auto 2k is quite alright to use on boat ect with no problem.although if used on the bottom and left submerged than a overcoat of antifoul would be recommended.
 
[ QUOTE ]
thinners wont damage the gel its not really strong enough to unless continiously left on or really rubed with a rag,
whereas cellulose thinners will melt the gel.

[/ QUOTE ]

... but the thinners are in the paint, so will remain in contact with the gel coat until they have evaporated off, so care IS required that the specific paint in use will not damage or soften the gelcoat in any way. Many thinners are perfectly OK - otherwise it would not be possible to paint GRP, but others most certainly will attack the resins, so you need to be sure the paint selected is not one of these.

[/ QUOTE ]

i spray grp commercials for a living all in 2k no problems whatsoever af 2k thinners in the paint attacking the gel/grp

carbody styling kits are nearly all made fro grp and painted in 2k to match the car again all done in 2k in sprayboots and lowbake ovens all with no problem
 
Hi Tyrone!
When I sprayed Cyano I used two-pack acrylic car paint from that place in Qormi. Had never sprayed anything larger than a model before.
That was 6 years ago. The sun that we have has not done much to it. Cyano only comes out for three weeks towards the end of May.
Regarding the undercoat, I used a 'filler / primer' that was light grey, the idea being that it was easier to check progress with the white topcoat. It was easier, no doubt about that. However, were I to do it again I would use white and not grey, the reason being that a scratch that goes through the white will show up more when the grey is exposed.
I didn't think that Eagle Bay would need spraying. She's a pretty fast boat, well underrated for racing /forums/images/graemlins/wink.gif
 
Watch my lips (er... keyboard?)... I didnt say 2k was a problem with GRP: What I said was that SOME thinners will dissove polyester resins. Others are fine - 2k included. For the amateur without professional knowledge of thinners, and paint chemistry, considerable caution is needed not to end up with an expensive and total disaster.
 
Hi Wally,

I went back to my post of last december since i'm now seriously thinking of spraying eagle bay this winter.

Just a question, when you sprayed Cyano did you spray on the gel coat or did she have a previous coat of paint ?

i'm wondering if i need to remove eagle bay's paint completely down to the gel and then start of with the filler/primer or if i can just sand down and fill and spray straight onto what i have.

Any help would be appreciated.

By the way how many litres of paint did you buy for cyano.. just so i get an indication?

Regards & happy boating
Tyrone
 
[ QUOTE ]

Just a question, when you sprayed Cyano did you spray on the gel coat or did she have a previous coat of paint ?

i'm wondering if i need to remove eagle bay's paint completely down to the gel and then start of with the filler/primer or if i can just sand down and fill and spray straight onto what i have.
......
how many litres of paint did you buy for cyano.. just so i get an indication?


[/ QUOTE ]

Cyano had been painted with a 2-pack something before - brushmarks and all! Test a scraping of your paint with acetone. If it dissolves, then the paint that you have is probably not 2-pack and will have to be removed completely if you intend to use a hardener type of paint.

I did rub down all of the paint until I got to the original gelcoat. I would suggest that you do the same. You'll know exactly what there is under the coating and you can make good any part that is not to your liking. It is not too difficult if you use a proper, man-size (what we here refer to as a) vibrator. Mine is a Makita, Very heavy, very reliable, and quite capable of carrying on when you are feeling your arms ready to drop off!

Re the quantity, I'm afraid that I don't remember the number of litres that I had bought. I suppose that I still have the receipts - somewhere. We're talking about 1999! I remember making similar noises at the time. There's no need to, really. By the time that you are through with the filler/primer you'll be able to make a pretty accurate guess as to how many litres you'll need. If you're staying 'white' there is even less of a problem because that colour is available 'off the shelf'.

What I do remember is that to do the blue line below the toerail, and another one close to the waterline I needed to order half a litre of 'Subaru Crystal Blue', which happened to match the vinyl that I had for the lettering, and I only used about half of that. If you intend to have a green line you'll probably have to do similarly. As far as matching a particular colour, take a sample with you and get one of the clients - car sprayers - to do it for you. They do it all the time and are able to indicate slight differences that you'll only be aware of when they point them out!

One last thing, If you're going for the 'hardener' type of paint, make sure that you are doing it in a well ventilated place i.e. outdoors; if you're doing it under cover then you must have an air-fed mask.

Good luck and keep in touch. On pontoon B most saturday evenings; if not there, then at Mellieha for the weekend.
 
I have sucessfully sprayed quite a few yachts using International 709 and 900 series paints.

I have an air fed mask which I always supply from a seperate remotely located compressor.

I use a 1.2mm nozzle.

The paint needs thinned down to get the correct viscosity. There are also other addatives that can be used.

In the right conditions by the time you put one layer on it is possible to just carry on with the subsequent coats.

A glaze coat on top can have a dramatic effect.

You can spray direct on GRP if it is sanded down and fully degreased. A rough hull can be sorted out by using low density filler, long sanding boards then high build filler and more sanding.

A sanding board can be easily made. Use a strip of 8mm ply, 4" wide 5' long with two handles 4" x 2" x 1" fixed aprox 4" from each end, then staple a 4" wide 5' 8" long aluminium oxide strip to the board at either end beside the handles.

Make several all with different grades of grit.

If a hull has previously been painted with one part paint I wouldn't try to spray it.

Just my tupence worth

Iain
 
You must log in or register to reply here.

Share this page

Top