Sand N Seal + Varnish

[Adam RejzlParticipant @adamrejzl26595]

Hi Folks,

I'm working on my first boat, and Aeronaut Diva. Good fun so far but I just wanted to check something before I slather the boat with sealer!

The instructions say to give the whole boat a covering of sanding sealer (I'm using Sand 'N' Seal) before finishing. I'm just wondering if the yacht varnish will work properly over Sand 'n' seal on the lovely mahogony tops? The Sand 'n' seal website says all types of paint are OK, but doesn't mention Yacht Varnish (I have proper International from my Wooden Dinghies).

Anyone have any tips or advice for this use case please?

Thanks

Adam

[Adam RejzlParticipant @adamrejzl26595]

Asking for advice about finishing a Diva model

[Richard SimpsonParticipant @richardsimpson88330]

Hi Adam and welcome to the forum.

Despite the likely hood of advice coming from all directions the only way to be 100% sure, which also takes into account ambient conditions, varnish age and condition etc..etc.. is to do a test piece.

Prepare a scrap of the model wood in exactly the same process as you have used for the model and put it through your intended finishing process then leave for a week or two.

Just a couple of hints to help achieve the best results:

1) Work in a clean dry dust free atmosphere.

2) Minimise humidity and ensure consistent temperature.

3) Ensure the base coat is thoroughly hardened before applying a different system of top coat to ensure all volatiles have been evaporated. Certainly a few days, preferably a week. to be sure.

[Colin BishopModerator @colinbishop34627]

Hi Adam,

You should have no problems in applying yacht varnish over Sand 'N Seal as it is designed to take any kind of surface finish. I've used aerosol can paints over it with no problems.

However, as with all these situations, take out insurance by making up a test piece using off cuts or similar wood.

In full size practice people often recommend sealing with a thinned down coat of vanrish (10% white spirit/thinner as do International) so you could try a test piece doing that as well. From what I have read I suspect using Sand 'N Seal may do a better job though. There's no substitute for making up a couple of test pieces before you commit yourself.

Snap! just seen Richard's advice! Sand 'N Seal has no volatiles as it is a water based acrylic. The yacht varnish does of course.

Colin

Edited By Colin Bishop on 20/02/2022 10:33:35

[Richard SimpsonParticipant @richardsimpson88330]

Surely then the "volatile" is water?  

Edited By Richard Simpson on 20/02/2022 10:51:29

[Colin BishopModerator @colinbishop34627]

Yes you are right Richard, I should have referred to VOCs.Sand 'N Seal can be sanded within an hour at room temperature.

Colin

[Adam RejzlParticipant @adamrejzl26595]

Thanks folks for the advice. I don't know why I didn't think of that!

I'll do test pieces as you suggest. Plan to do 1 Sand 'n' seal + Varnish, 1 thinned varnish + varnish and 1 with just normal varnish coats and see what looks / works the best.

Will let you know what I find!

[ashley needhamParticipant @ashleyneedham69188]

Adam. “I don’t know why I didn’t think of that” usually comes after you have done it and it goes wrong, so asking first is spot on and absolutely the right thing to do.

As a generality, I have found any sort of painted polyurethane paint/varnish goes over any brushed acrylic coating no probs when fully dry, but this is not the case with spray (can) finishes.

My current undercoat, Rustins acrylic, works ok with Halfords spray acrylic spray cans and all the polyurethane spray cans I have tried, but I would always test any ‘new’ make of spray can first.

Ashley

[Former MemberParticipant @formermember67585]

[This posting has been removed]

[ashley needhamParticipant @ashleyneedham69188]

I must say I only used varnish when I did my veneering. Other sealers may work ok but essentially you have two different finishes on the wood and the underneath one I suspect will be harder than the top one.

I had forgotten how (relatively) soft yacht varnish is and how long you need to leave it between coats and rubbing down. It’s the flexibility that gives it durability on a material that expands and contracts quite a bit.

Lets put it this way, if you only use yacht varnish, you are guaranteed a “best” finish rather than worry about using other products, or that’s the way I look at it?.? (Also you only buy one tin of varnish and not TWO tones of something!)

ultimately, does it make a difference? Don’t know.

Ashley

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