Prep After Soda Blasting

[Hookup1]

Do you need to apply a primer or epoxy barrier coat after soda blasting the bottom paint off?

 

[Jimmyfiretruck]

No
You’re gonna need to “finish sand” and wipe it all down with a solvent

Keep this in mind :
Barrier coat - number of coats means nothing ! “Coverage “does
You’re gonna need both colors of barrier coat ,white and grey.alternate colors, to assure full coverage. Barrier needs to be 10mil thick, mil guage or a matchbook cover,measures the thickness.

 

[SkunkBoat]

yes

 

[Jimmyfiretruck]

yes

What exactly are you priming with ?

You do know what epoxy barrier coat is, right ?

 

[Hookup1]

Yes Stevie I do know what epoxy barrier coat is. I use it whenever I disturb the bottom. Bow thruster and transducers installs for example.

It has been my understanding that soda blasting will remove the bottom paint without etching the gelcoat. Sandblasting is different - it will destroy the finish on the gelcoat and requires a barrier coat to be applied first.

I have to check receipts (previous owner) but my boat was soda blasted 15 years ago, a grey primer was applied and then bottom painted with Petite HydroCoat. No problem at all with the bottom.

I would like to hear from someone who has actually soda blasted their bottom and what if anything they did to prepare it for bottom paint.

 

[SkunkBoat]

What exactly are you priming with ?

You do know what epoxy barrier coat is, right ?

Prime with an epoxy barrier coating if you are going to put on antifouling paint and keep the boat in the water. That is a technically a primer.

yes, I do

You could get away with different cheaper easier primers/tie coats but why go thru all the expense of sodablasting to cheap out on primer.
I have not done an entire hull but I have done a transom and bottom repairs and always replace the epoxy barrier coat before the antifouling paint.

 

[Jimmyfiretruck]

Prime with an epoxy barrier coating if you are going to put on antifouling paint and keep the boat in the water. That is a technically a primer.

yes, I do

You could get away with different cheaper easier primers/tie coats but why go thru all the expense of sodablasting to cheap out on primer.
I have not done an entire hull but I have done a transom and bottom repairs and always replace the epoxy barrier coat before the antifouling paint.

You do understand , the gentleman was asking if he needs to put on a primer, before barrier coating

 

[Jimmyfiretruck]

Yes Stevie I do know what epoxy barrier coat is. I use it whenever I disturb the bottom. Bow thruster and transducers installs for example.

It has been my understanding that soda blasting will remove the bottom paint without etching the gelcoat. Sandblasting is different - it will destroy the finish on the gelcoat and requires a barrier coat to be applied first.

I have to check receipts (previous owner) but my boat was soda blasted 15 years ago, a grey primer was applied and then bottom painted with Petite HydroCoat. No problem at all with the bottom.

I would like to hear from someone who has actually soda blasted their bottom and what if anything they did to prepare it for bottom paint.

That’s incorrect - sand / soda blasting leaves a profile on the bottom - it indeed removes bottom paint there sparky …
Clearly,you’ve not much experience with these sort of things huh ?
There’s going to be spots that will require finish sanding - I stated that …

As far as a primer before barrier coat - nothing , except for a solvent wipe down

Follow the instructions I gave, that’s how the pro’s do it - I know , I am one clearly, you’re not sparky …

 

[SkunkBoat]

You do understand , the gentleman was asking if he needs to put on a primer, before barrier coating

no he did not
He asked if he should prime or epoxy barrier before bottom paint.
I stand by my answer...yes

 

[Hookup1]

no he did not
He asked if he should prime or epoxy barrier before bottom paint.
I stand by my answer...yes

SkunkBoat -Thanks for the reply. I'm considering changing the bottom pant color (black to vivid white) along with my re-paint project. I have to strip a few inches along the edge to shoot the hull sides. Before committing to a new bottom color just wanted to get an opinion on approach and what is involved. Thanks for the help.

New color will be a custom AwlCraft 2000 MixIt color. Originally going to be F5304 but going lighter F5833.



Stars & Stripes is a great color but I think it looks better on bigger boats. Too dark for me. Sky Blue too dark, light blue too light. I wanted a softer island color. This is it!

 

[SkunkBoat]

I'm assuming the existing barrier coat will be gone or compromised by soda blasting.
I wouldn't paint directly to the sanded gelcoat. I would fix all the dings and fair them and do a new epoxy barrier as a primer for new bottom paint.
It can be used under topside paint so overlap isn't an issue. All the brands will do.
So yes, new barrier is a given.

Are you going to prime for the AwlGrip? They have a topside primer and a "Hull-guard" primer for above & below

Your big question is which bottom paint for your circumstance. Trailer? In water a lot? Docked? Ablative? Multiseason? Hard paint?

You don't want to go thru soda blasting and priming and then F up on the bottom paint choice and have to strip it later to change types.

 

[Hookup1]

I'm assuming the existing barrier coat will be gone or compromised by soda blasting.
I wouldn't paint directly to the sanded gelcoat. I would fix all the dings and fair them and do a new epoxy barrier as a primer for new bottom paint.
It can be used under topside paint so overlap isn't an issue. All the brands will do.
So yes, new barrier is a given.

First pass on painting the hull a 4" strip of bottom paint will be soda blasted, sanded clean and a barrier coat applied. Black Pettit HydroCoat will be re-applied. Too much to do to also take a complete bottom on right now. The black bottom will look good with new blue hull color.

Are you going to prime for the AwlGrip? They have a topside primer and a "Hull-guard" primer for above & below

Above the waterline I'm using AwlGrip 545 primer. For example the hardtop all loose gelcoat chipped off, sanded out, primed with 545 (brushed) and AwlFair buildup started. I also repaired where the rigger bases were with Coosa board. Applied fairing to edges, covered with release fabric, smoothed out. Going to shape them today.



Once the rough work is done it will be primed with 545 and finished with AwlCraft 2000. Everything sprayed. Top will be Brightside White Revisited and underside will be F5833 (Pantone 2985C) Light blue. I going for a look like this (except for the models!)



Topside and hullsides will get the same treatment. I'm also pulling the aluminum hardtop frame off. This will be primed with AwlGrip's aluminum primer, 545 primer and painted with Brightside White. Focusing on getting everything the hardtop frame sits on refinished before moving on to topside and hullsides.

Your big question is which bottom paint for your circumstance. Trailer? In water a lot? Docked? Ablative? Multiseason? Hard paint?
You don't want to go thru soda blasting and priming and then F up on the bottom paint choice and have to strip it later to change types.

Undecided on what to do long term with the bottom. This isn't a big deal for me. May stay this way or possibly try a blue bottom paint.

Whatever I do it will get soda blasted, barrier coat and painted. I like the Pettit Vivid White. This is a hard paint. I have a storage customer with a big center console that uses it and it look great. He leaves the boat in the water. Some of the GW guys say you have to scrub it often or it looks like crap.

 

[seasick]

No
You’re gonna need to “finish sand” and wipe it all down with a solvent

Keep this in mind :
Barrier coat - number of coats means nothing ! “Coverage “does
You’re gonna need both colors of barrier coat ,white and grey.alternate colors, to assure full coverage. Barrier needs to be 10mil thick, mil guage or a matchbook cover,measures the thickness.

I agree that light sanding will probably be needed in some areas, maybe all. There is also a decent chance that some damaged/gouged,etc spots will be found that need repair.Maybe blisters too.
A barrier coat is a prudent move since soda blasting can also be quite aggressive depending on the skill of the technician and to an extent, the type and condition of old bottom paint.. For what it costs to blast, it would be penny wise , pound foolish not to barrier coat
For prep, read the instructions for your barrier coat. Follow those instructions for wipe down. It varies by paint brand and type

I sort of agree about coverage, not coats but for products like Interprotect 2000 a proper final thickness is important and to get to that thickness, multiple thin coats applies at specific time intervals is critical. I like how the 2000 works but it quite labor intensive to apply. If the paint manufacturer specifies 4 to 6 coats and the marina says nah, it only takes two, I would find another marina.

In the rare cases where blasting reveals a good condition old barrier coat, a new coat may not be needed, just the recommended bottom paint prep and paint.

 

[Hookup1]

I’m sure they used a one part primer on my boat. Likely come off with soda blasting. Be interesting to see if the Interprotect 2000 areas comes off.