Can anyone recommend a high-build epoxy primer?

A

Avocet

Well-Known Member
Joined
3 Jun 2001
Messages
30,755
Location
Cumbria
Visit site
I've been replacing Avocet's topside gelcoat over the last few years with a mixture of SP 106 resin and microballoons. The original gelcoat was covered in a fine maze of cracks. Oddly, it's fine on the underwater surface, and any surface that has had paint on it (there's a painted stripe down each side). This makes me think it was an ultraviolet problem, but anyway, one way or another, it's gone now!

I'm at the point where it has been sanded with 60 grit paper and there are almost certainly a few "imperfections" still there. I want to give it a few coats of high-build epoxy primer next. Can anyone recommend anything? I've been wondering about SP "Eposeal", Hempel (Blakes) "Epoxy Primer Undercoat", or International's "Interprotect". Also considering Awlgrip 545.

Any suggestions / opinions please?
 
Just a few thoughts, have you decided what top coat you will use? and will it will be compatible with the brand of primer you select?

It might be worth thinking about what top coat you plan to use and select a primer based on that.

As you know I am a fan of the International range of paints and prefer the 'industrial' products over the domestic, however this can be very costly.

Interprotect is a good product, particularly below the waterline in my experience, a mist coat followed by a half coat will show up most imperfections and provide very good protection when applied as per instructions when full coating, also fast curing between coats.

Also note, a mist coat below the waterline just prior to antifouling will provide a good key for the antifoul and a good indicator when cleaning later.

No doubt this posting will attract several responses and should make interesting reading.

Avagoodweekend......:)
 
Last edited:
Sigma 280, does a stunning job as long like all coatings, you apply enough of it. Roller, brush or spray apply. Like most epoxies, it can be thinned with xylene (they all like to sell you their special secret and expensive solvent) You already know tool clean up is with non brewed condiment (Aqueous acetic acid)
 
Bobobolinsky said:
Sigma 280, does a stunning job as long like all coatings, you apply enough of it. Roller, brush or spray apply. Like most epoxies, it can be thinned with xylene (they all like to sell you their special secret and expensive solvent) You already know tool clean up is with non brewed condiment (Aqueous acetic acid)
Click to expand...

Don't think you can thin epoxy with Xylene, methanol is what you want. Also, ascetone is better than vinegar for cleanup but IME nothing works very well for that.

Hth,

Boo2
 
If you check the data sheets on epoxy thinners, most show xylene as the major constituent. Penetrating epoxy is resin thinned 10-20% with xylene, and if you go to a professional coatings company, they will not go anywhere near methanol, because of it's nastier properties, like invisible flame, low flash point and reactivity. Yes it can be used to thin paint, but with it's proclivity for water, it also causes epoxy blush and failure to cure.
 
have tried a few epoxy high builds in the course of my work,

favorite has got to be awlgrip's awl-quick, but is 'king exspensive (£500 per US gallon)

international 880 (i think) is nearly as good at a fraction of the price (£80 for 2l)

wessex resins do one (pro-set 320 or 360) whcih roll's on ok, but i didn't have much sucess spraying it.

Marineware did a cheapo one (£50 for 2l) which I didn't get on with, but i know other people who have

these are all high solids products, which will give 0.5 - 1mm of build in a few applications (2 for awl-quick, 5 for proset) and then sand back very easily (120g) to a very fine surface ready for undercoat

for my money it would be the international product followed by there 2 pot base coat & top coat.

for ultimate logevity & quality of finnish, awl-grip all the way tho
 
Bobobolinsky said:
If you check the data sheets on epoxy thinners, most show xylene as the major constituent.
Click to expand...

Well, it seems I stand corrected. West have some details of thinning epoxy here and although they do mention the use of methanol they also suggest laquer thinner which does have a xylene component. Personally I'd use methanol every time, just because things like acetone and xylene give me a raging headache whereas the effect epoxy + methanol can be kept at bay by using a facemask and gloves. No such luck with polyester resin :(

Boo2
 
Thanks all - especially Seasolutions for a very detailed run-down!

I'm not sure I need 1mm of build - or even 0.5mm to be honest. Besides, thought I love it dearly, I can't justify cashing out £500 just now! There's a moulded cavetta line down each side which has a few fairly small detailed recesses in it and I think I'd loose those with such a high build. The rest of the hull is (and I tempt fate here!) pretty fair now. I'm sure there are a fair few small defects, but I don't think there are many (if any) large hollows - by which I mean very shallow ones extending over an area of several square inches. I've been careful never to sand by hand and always use either a long bed sander or Oldsaltoz's aptly named "torture board". That said it's hard to be sure until it's all one colour and has a bit of a shine on it. If I spray the primer on and find it looks like a clinker-built wooden yacht, I'll know I didn't get it quite right!

Last question: Presumably any epoxy primer will stick to the SP 106 and microballoon mixture that's already on there? It's currently flatted with 60 grit.
 
Avocet said:
Last question: Presumably any epoxy primer will stick to the SP 106 and microballoon mixture that's already on there? It's currently flatted with 60 grit.
Click to expand...

Yes.

But I would buzz over with 120g on a power sander first, followed by 240g if your feeling fussy.

Scribble over the whole hull with a soft pencil then sand off the pencil marks - your just trying to remove the 60g marks which will show through the paint. (you can buy marker coat from paint companies such as u-pol, this comes in an aerosol, so is a bit quicket to apply)

any good base coat has a slight sheen to it, this is, as you say, when you really know how fair it is......

if your spraying, it should be pretty easy to build up approx 0.3mm of base coat (recomended thickness for 545 IIRC)
 
seasolutions said:
Yes.

But I would buzz over with 120g on a power sander first, followed by 240g if your feeling fussy.

Scribble over the whole hull with a soft pencil then sand off the pencil marks - your just trying to remove the 60g marks which will show through the paint. (you can buy marker coat from paint companies such as u-pol, this comes in an aerosol, so is a bit quicket to apply)

any good base coat has a slight sheen to it, this is, as you say, when you really know how fair it is......

if your spraying, it should be pretty easy to build up approx 0.3mm of base coat (recomended thickness for 545 IIRC)
Click to expand...

Oi,
If I hear a power sander after all that torture boarding, I'll be there in a flash with a fire hose to put it out.

Avagoodweekend......
 
oldsaltoz said:
Oi,
If I hear a power sander after all that torture boarding, I'll be there in a flash with a fire hose to put it out.

Avagoodweekend......
Click to expand...


LOL :)

fair point, I sometimes forget that not everyone has spent whole weeks of their life pushing sandpaper around - you can do a lot of damage, even with an oribe if your not careful.
 
Sadists, the pair of you!!!

After a relatively short period on the "torture board" my standards in terms of finish are soon reduced! In fact, I'll be happy if people don't graze themselves on it when they brush past!

Spoke to the place I got the epoxy from today and they recommended "Nortex HPE" sprayable high build primer. OK, so that was over the phone but I've tried searching for various spellings of it with no success! Apparently about £60 for 2.5 litres. By the way how much to do the topsides of a 27 footer? I guess we're talking about 15-20 square metres.
 
seasolutions said:
have tried a few epoxy high builds in the course of my work,

favorite has got to be awlgrip's awl-quick, but is 'king exspensive (£500 per US gallon)

international 880 (i think) is nearly as good at a fraction of the price (£80 for 2l)

wessex resins do one (pro-set 320 or 360) whcih roll's on ok, but i didn't have much sucess spraying it.

Marineware did a cheapo one (£50 for 2l) which I didn't get on with, but i know other people who have

these are all high solids products, which will give 0.5 - 1mm of build in a few applications (2 for awl-quick, 5 for proset) and then sand back very easily (120g) to a very fine surface ready for undercoat

for my money it would be the international product followed by there 2 pot base coat & top coat.

for ultimate logevity & quality of finnish, awl-grip all the way tho
Click to expand...


I've found some "Interprime 880" - is that the stuff?

http://iyp.yachtpaint.com/uk/default.asp

(OK, that's a less than helpful URL)!

This stuff:

http://secure.international-coatings.com/pds/yacht/GB_ISO_M_5000139.htm
 
Last edited:
Just to help out heres a list of ones I've used in the past to help you chose:

Nautix HPE, high build primer can be used above and below the waterline either a a high build primer to go straight to topcoat, or as an antifoul primer for a water barrier protection. Timing for sanding this is critical too soon and it clogs the paper, too long and its too hard.

International 820, above water only can be topcoated straight on top but better if coated in 880

International 880, finishing primer above water only

Epifanes epoxy primer, finishing primer for above water only. Good budget primer but takes a while to cure.

Awlgrip High build, good and expensive needs a finishing primer over the top else sucks the gloss from the topcoat. Above water only.

Awlgrip quik grip, quick drying and can be over coated with topcoat but really needs a finishing primer over the top.

Awlgrip 545, premium finishing primer, should be used under Awlgrip topcoats for hte best adhesion and finish.

Durepox, usually used in the race boat market but very quick drying and overcoating primer, not much build but you can put it on so quick doesn't really matter. Only problem is it cures so hard if you've left it to long before you sand it, it can be a real bugger.


If you've got 60 grit scratches at the moment no matter what you use they will still show, best to get it down to 120 grit and finer and your risking the paint not sticking.

My personal preference is HPE, my whole boat is coated in it from a full renovation.
 
You must log in or register to reply here.

Share this page

Top