Boat painting help

[BPSparks]

Good day

I'll be as brief and to the point as possible.

 

After many, many hours of preparation, I am ready to begin the painting process of my topside.

 

Products being used are International's Pre-Kote as my undercoats (no primer needed) and Toplac as my finishing coats.

2.5 coats of undercoat and 2.5 coats of finish. The 1/2 coats are a blend of the two products 50/50.

 

Ok. The questions are coming soon.

International recommend that the undercoat is applied to a surface abraded to 180-230 grit.

As I have had to use 80 grit to remove the old paint completely, my first question is can I apply the first coat of undercoat to the 80 grit surface?

To my thinking, 80 will give me a better key thus better adhesion.

or should I sand up to 180 before applying first coat?

 

Following on, if I do apply to the 80 grit surface, will I need to sand up to 180 for the next coat? or ever?

 

Which leads to my last question, should I be sanding between each coat? or between undercoat and finish coats?

 

I hope someone with some experience in boat painting can offer some advice.

 

Thanks for your time.

 

BPSparks

 

[bizzard]

Good day

I'll be as brief and to the point as possible.

 

After many, many hours of preparation, I am ready to begin the painting process of my topside.

 

Products being used are International's Pre-Kote as my undercoats (no primer needed) and Toplac as my finishing coats.

2.5 coats of undercoat and 2.5 coats of finish. The 1/2 coats are a blend of the two products 50/50.

 

Ok. The questions are coming soon.

International recommend that the undercoat is applied to a surface abraded to 180-230 grit.

As I have had to use 80 grit to remove the old paint completely, my first question is can I apply the first coat of undercoat to the 80 grit surface?

To my thinking, 80 will give me a better key thus better adhesion.

or should I sand up to 180 before applying first coat?

 

Following on, if I do apply to the 80 grit surface, will I need to sand up to 180 for the next coat? or ever?

 

Which leads to my last question, should I be sanding between each coat? or between undercoat and finish coats?

 

I hope someone with some experience in boat painting can offer some advice.

 

Thanks for your time.

 

BPSparks

I think you need to sand or flat down before every coat and complete that coats process the same day especially if working outside. There's too much muck and fumes in the air not to, one of the reasons I think why some folk keep complaining about strange things happening to their paintwork later on like peeling off, strange patches, blotches and blisters appearing.

 

If your using a good quality random orbital sander, air or electric the 80 should be ok until you begin on the last gloss coats then the 180. Before the last top coat I'd wet n dry ''wet'' with about 400- 600 paper.

Edited May 23, 2013 by bizzard

[alan_fincher]

Products being used are International's Pre-Kote as my undercoats (no primer needed) and Toplac as my finishing coats.

2.5 coats of undercoat and 2.5 coats of finish. The 1/2 coats are a blend of the two products 50/50.

Why do you think no primer is needed?

 

If you have gone back to steel, then surely you need primer.

 

This is what the Pre-Kote datasheet says about painting steel......

 

 

STEEL

Degrease with solvent or Super Cleaner. Gritblast to Sa 2½

- near white metal surface.

If gritblasting is not possible, grind the metal surface with 24 - 36 grit abrasive discs to a uniform, clean, bright metal surface with a 50 - 75 microns anchor pattern.

Use angle grinder on small areas.

Clean thoroughly and allow to dry.

Prime with Yacht Primer

[BPSparks]

Why do you think no primer is needed?

 

If you have gone back to steel, then surely you need primer.

 

This is what the Pre-Kote datasheet says about painting steel......

 

My boat is GRP

 

"complete that coats process the same day "

Can't - minimum overcoating times are 24 hours. 30 hours before you can sand.

 

All your info makes sense and its pretty much what I thought needed to be done.

[bizzard]

My boat is GRP

I had a sneaking suspicion that it might be, why I didn't comment on that part.

[alan_fincher]

My boat is GRP

Ah! That's different!

[bizzard]

Polyurethane paint I believe is best for GRP, International Brightside used to be but I don't know about Toplac.

 

If you painting onto GRP, Gel coat you will need the etching primer.

Edited May 23, 2013 by bizzard

[BPSparks]

Polyurethane paint I believe is best for GRP, International Brightside used to be but I don't know about Toplac.

It is.

I did read that in cases it may be too glossy for its own good as it shows all the bumps and warts.

I'm good at prep, but probably not that good....

Toplac is the next step down, still glossy but a bit forgiving.

its basically a 1 part system

 

Toplac is Brightside I think

the 2 part polyurethane is what i was refering to above

Edited May 23, 2013 by BPSparks

[Ex- Member]

Ok. The questions are coming soon.

 

International recommend that the undercoat is applied to a surface abraded to 180-230 grit.

 

As I have had to use 80 grit to remove the old paint completely, my first question is can I apply the first coat of undercoat to the 80 grit surface?

 

To my thinking, 80 will give me a better key thus better adhesion.

 

or should I sand up to 180 before applying first coat?

 

 

No 80 grit will give a good key, but denib following coats with 180 then to 240 grit as you get to final coat.

Following on, if I do apply to the 80 grit surface, will I need to sand up to 180 for the next coat? or ever?

 

 

 

You should always sand between coats, but not necessarily fully, you need to remove any imperfections though that appear from the first coat, like runs - nibs flies/insect marks. Basically a flick over or de-nib. Then dust down & degrease, I would invest in tack rags, basically a sticky cloth that removes fine particles and dust from the painted surface.

 

Which leads to my last question, should I be sanding between each coat? or between undercoat and finish coats?

 

 

Yes as above. Sand between every coat, It's called de-nibbing and tack rag also. http://www.amazon.co.uk/dp/B006SHGTI6/?tag=hydra0b-21&hvadid=10340519829&ref=asc_df_B006SHGTI6

I hope someone with some experience in boat painting can offer some advice.

 

 

 

Thanks for your time.

Edited May 23, 2013 by Julynian

[BPSparks]

Thanks so much for your reply Julynian..