Thread: Painting guide/help

It's a great day with all that scraping is finished. Well done!!!

MIK

It was a great day until i realised i have a heap of sanding to do. Im now trying to sand back the epoxy finish in the interior. It loves to eat the sandpaper thats for sure.

Do i need to sand to a point where the entire surface is dull? After the sanding so far it has tiny areas where the sander doesnt get to.

Cheers

Ace

A trick I've used to sand inside dagger and centerboard cases is to take a long drill bit or length of straight rod and tape some paper to the end of it. I tape the paper along say 3" at the end of the rod, then wrap the excess paper around counter clockwise, to let it "flap". With the rod chucked in a drill it can be inserted into the case from above or below and worked around the inside. The corners will still need to be sanded by hand with sticks, but the bulk of sanding can be done this way. In fact, have a few broken 18" tip masonry bits that are now used for this purpose. This is partly because it's not worth the trouble welding on new carbides to the end of the bits and now that the used beltsander paper is well taped on the bit, I don't want to remove it until it's good and shot.

Another good tip i may just have to try. Thanks for that.

Ace

Howdy,

If you don't need to coat the epoxy again it doesn't need to be sanded.

If you applying another coat of epoxy you are doing it the really hard way. You can apply the epoxy wet on wet - if a coat is allowed to go tacky you can do the next coat after.

If painting you need to sand it enough to get rid of the shine. 180 or 220 grit paper.

MIK

Hey,

At this stage im planning to paint, thats why im giving it a sand. The repairs that were done before i got the boat dont look too good.

As i said in the previous post there are small "lows" in the epoxy that the sander doesnt get into. Im using 80 grit. Is it imperative that every square inch is dull? Also, is there any problem with putting down a coat or two of primer over epoxy/bare timber? Reason i say it that way is that there are some bare spots of timber (weathered sections) and the other parts are still sealed with epoxy (shaded parts and more towards the bow of the boat).

Cheers

Ace

Another question.....

As mentioned before i have the skin of the rear flotation tank to replace with 3mm ply. Towards the ends of the sheet it bends up to meet the rail.

I was wondering, is there a chance the epoxy will crack when i bend the ply to meet the shape? thus not sealing the ply. Being a flotation tank, i will have to seal it first with epoxy then glue down, obviously due to access.

Any tips?

Thanks

Ace

Originally Posted by highace1

Another question.....

As mentioned before i have the skin of the rear flotation tank to replace with 3mm ply. Towards the ends of the sheet it bends up to meet the rail.

I was wondering, is there a chance the epoxy will crack when i bend the ply to meet the shape? thus not sealing the ply. Being a flotation tank, i will have to seal it first with epoxy then glue down, obviously due to access.

Any tips?

Thanks

Ace

PAR discussed this recently in another thread and the general gist of his argument was, I believe, that epoxy is as flexible as the timber ie, if the timber can take it, the epoxy will too.

When sealing the underside of a tank top, where practical, try to do the three coats wet on wet but glue it down immediately you appy the last coat - if you can manage it, this is efficient in time and ensures a chemical bond between the sheet and what you're trying to glue it to. It's also good fun as you feel like you've achieved two jobs in one hit.

Richard

If not wet on wet, glue the top down within 25 hours while the epoxy is cured, but still very flexible. Epoxy cures to within 80% of full hardness in 24 hours, but can take a week to get that last 20%. During this time the epoxy will be more flexible then when fully cured. I don't think you'd have trouble if it was fully cured, but it doesn't hurt to work the "percentages".

I'd be with Richard about the underside - do a trial run first.

Then do the top after you remove the temporary fastenings.

With all tricky gluing jobs, do a dry run first.

MIK

That will work out fine then, just have to find 3mm ply. I want to avoid getting it shipped in purely due to cost. I Last time i looked i was up for around $40 shipping from Boatcraft. Not their fault though, bloody couriers!

About the sanding....there are many little "lows" in the epoxy that the sander doesnt get into. Im using 80 grit. Is it imperative that every square inch is dull ( sounds like im being lazy)?

Also, is there any problem with putting down a coat or two of primer over epoxy/bare timber? Reason i say it that way is that there are some bare spots of timber (weathered sections) and the other parts are still sealed with epoxy (shaded parts and more towards the bow of the boat).

Cheers

Ace

Hi Alex

Did you call Mr P & W at all? Just wondering if they could help with your 3mm ply or not?

No, i havent yet. I will try but after having a look on their website they dont seem to stock any. Only 4mm.

Hopefully i can find some.

Ace

Don't forget, they probably used 3mm because that's what they had. I'd take good quality 4mm over poor quality 3mm any day. Give bloggs1968 of this forum a pm - his business is, (I think, maybe I'se mistook) is reasonably local and has imported some top quality ply and may be able to help.

Mr Ply and Wood used to be good but there have been some concerns on here recently, still worth a call though - if I remember rightly, the business has split up a little (please correct me if I'm wrong).

Duck Flats are another source but you've probably going to get the same transport costs as with Boatcraft

Believe it or not, Bunnies may be able to help ... and very probably won't be able to either but I have heard of people being able to get decent ply at decent prices through them - it depends on the stage of the moon, the particular shop and which robot they've got manning the phone this week but they're worth a call if all else fails. Just be sure to specify marine ply.

Richard