Just practicing some painting on a hatch before doing the whole deck. Im using International Perfections Undercoat. The first coat ended up with lots of tiny bubbles which look like pits when dried. Some advice was to let the pot of paint sit after missing and Internationals technical sheet says leave for 5 minutes. I also sanded out the bubbles where possible with approx. 280 grit.

So for the second coat I left the cup of paint for 10 minutes and there were still microscopic bubbles in the cup. I tried popping them with a paddle pop stick but after applying the second coat the coat is now full of little bubbles as it dries. Any advice would be greatly appreciated.

what kind of roller are you using?Did you go back over super lightly with the roller to pop the bubbles?

You could also mix in some No. 9 thinner to give you more time to go back over and pop bubbles.
A pad brush works well, ideally get someone to help you.

Thanks. I was just using a brush as it is a small area. When I do the deck I will use a roller though. Would you think I experience it less with a roller? I'll get some thinner when I do the deck. Thanks.

I haven't experienced bubbles with a brush.
not such an issue now as only your primer so will be sanded out anyway.
could have been temp? Ideally try and paint when over 20 degrees. Not in direct sunlight and not in the afternoon.
Def help with some No.9, it's a thinner and retardant.

On your deck, try and apply as thin as possible with more coats.
Paint should be more like milk consistency.
Thin foam roller. Tip off bubbles with foam pad.
Have plenty of spares.
Only mix what you need.

Personally I wouldn't tip it with a brush a quickly rolled area should self level to a perfect finish once you get the hang of it. If you can work in small areas at a time this will also help. Use little ripper mohair 5mm nap.

I rolled the deck head (roof)and forward bulkhead in two pack on my previous rebuild and the finsh was very close to being applied by spray. Being out of direct sunlight certainly helped.

Could be old wax was not removed properly, or pin holes in the fiberglass. To get a perfect mirror finish clean the surface with a wax & grease remover, then light sand it and clean again with acetone. I'd also use an epoxy primer first and tip it so you can see any pinholes that may appear, fill in the pinholes with a paddle pop stick or small plastic spreader then go over the surface with a torch to make sure there are no more pinholes. Sand lightly and apply another coat of primer then look for pinholes again, if there are none only then let it cure, light sand and apply the Perfection undercoat.

Sounds like maybe your going a bit too thick with the coat too. The tech data sheet says 76 microns a coat when wet, so not even 1/10th of a millimetre thickness The 38 approx microns you're meant to end up with dry leaves next to no space for bubbles (think sheet of paper thin)


i'd try using a foam mini roller (you'll need to use a paint tray as well to get it to spread evenly) available at bunnings in a similar form to southaces photo. They do tend to break apart after a while, but it'll do a much better job of knocking the bubbles out than a brush.

Water in the atmosphere will also cause it if you paint on a humid day, don't be tempted to paint too late in the day.

Awesome thanks. Ill try all of the above. I was deffinately putting it on too thick so will pick up some thinner. Ill try rolling.

I also painted late in the day on the first go.

At this stage I will skip the primer..... Its all getting very expensive and more and more complicated.

I have been using the Diggers Wax and Grease Remover and acetone so will keep doing that.

Ok. Now I am falling down the black hole of doom that is Google. I think I will use at least one coat of primer... then undercoat, then top coat for all non-skid areas.

Separately for the non-skid area the feedback from Kiwi grip is to clean, sand the diamond pattern a medium amount, clean then go right on top with no priming or undercoat. This should save some money.

I only use primer - epoxy high build primer. I have never used an undercoat. High build is a great paint, sands well and provides an excellent substrate. Try and stay away from Whitworths to buy primer or any paint. Go to Wattyl or Jotun stores and get a 5 litre pack. Go in your daggiest clothes at the start of the day, hang around with the tradies and say "Yeah Gday, I need some High build - UC 230" then they say account? I say just cash today and they give me a wholesale price. Same for topcoat - I use Poly U 400. Get good at using it and you can fix up all manner of paint issues without breaking the bank.

If you want the best brush on paint then a friend gets heaps of work using Alexseal. It does brush awfully well and he gets comments about whether it was sprayed. Expensive though.

If you want the bees knees then read Russel Brown's E book. I met him a few times and he is a real craftsman. He uses International and the book is based on that. I would think the money is worth the E book as his boats are always beautifully finished and he rolls the paint.

smalltrimarans.com/blog/ebook-by-russell-brown-shows-boatbuilders-painting-techniques/

So I am happy for some orange peel and use Wattyl and a roller (when I can't spray). My mate uses Alexseal and Russ uses International. We understand our paints. If you talk to painters they usually only like one or two types of paint they like. (We once got a painter for a job and he said he would only use US paints - it was a great job) I am happy with Wattly but if I was in your shoes I would probably read Russ' book and go with his advice. (Although I may sneak in some UC 230 if it was cheaper than the international topcoat)

Have fun and learn lots

Select to expand quote

Kankama said..
I only use primer - epoxy high build primer. I have never used an undercoat. High build is a great paint, sands well and provides an excellent substrate. Try and stay away from Whitworths to buy primer or any paint. Go to Wattyl or Jotun stores and get a 5 litre pack. Go in your daggiest clothes at the start of the day, hang around with the tradies and say "Yeah Gday, I need some High build - UC 230" then they say account? I say just cash today and they give me a wholesale price. Same for topcoat - I use Poly U 400. Get good at using it and you can fix up all manner of paint issues without breaking the bank.

If you want the best brush on paint then a friend gets heaps of work using Alexseal. It does brush awfully well and he gets comments about whether it was sprayed. Expensive though.

If you want the bees knees then read Russel Brown's E book. I met him a few times and he is a real craftsman. He uses International and the book is based on that. I would think the money is worth the E book as his boats are always beautifully finished and he rolls the paint.

smalltrimarans.com/blog/ebook-by-russell-brown-shows-boatbuilders-painting-techniques/

So I am happy for some orange peel and use Wattyl and a roller (when I can't spray). My mate uses Alexseal and Russ uses International. We understand our paints. If you talk to painters they usually only like one or two types of paint they like. (We once got a painter for a job and he said he would only use US paints - it was a great job) I am happy with Wattly but if I was in your shoes I would probably read Russ' book and go with his advice. (Although I may sneak in some UC 230 if it was cheaper than the international topcoat)

Have fun and learn lots

Great thanks. I have the Russel Brown book for epoxy and have just read this one. Only $5 for the eBook.

Thanks for the tips.

Just for others information in the future
I solved the bubbles issue by thinning and applying with a roller then tipping with a brush which popped all the bubbles. I was putting it on too thick and not tipping.

Nice one bro