Painting on CNC routed signs bleeding into grain

10579 Views 16 Replies 8 Participants Last post by Gary Wiant, Apr 13, 2019

Gary Wiant

Discussion Starter · Apr 7, 2019

I've been doing like everyone does. using spray paint to paint the routed sections then sanding off the paint to only leave the routed areas painted. But I've been noticing the paint bleeding into the grain. I've even painted the wood with sanding primer prior to painting but that didnt seem to make much of a difference.

Does anyone have any tips on ways to keep the paint from bleeding?

Will it be better to paint with a brush?

Does using an airbrush make any difference? I've heard that the atomized paint makes sanding easier.

Thank you
Gary

1 - 17 of 17 Posts

difalkner

· #2 · Apr 7, 2019

What kind of wood and paint, Gary? I have sealed bare wood areas with Nitrocellulose sanding sealer or Shellac and then painted with no real issues. I've used both brush and spray (rattle can). I've used my air brush for small areas but usually seal them first.

David

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Gary Wiant

Discussion Starter · #3 · Apr 8, 2019

David wood is all over the place, anything from rough cut, air dried pine, hemlock, white oak & maple to kiln dried pine, oak, cherry & maple.

How many coats of sanding primer do you use when you applying it?

Thanks
Gary

difalkner

· #4 · Apr 8, 2019

Not sanding primer, Nitrocellulose sanding sealer - clear, like I use on a clear lacquer finish. One will do it, or has. I suppose you could do two to make sure since it doesn't take long to dry.

David

Reactions: 1

JOAT

· #5 · Apr 8, 2019

Gary Wiant said:
I've been doing like everyone does. using spray paint to paint the routed sections then sanding off the paint to only leave the routed areas painted.

No, not every one. The few times I paint anything I use a brush, acrylic latex, and have never had any bleeding issues. :laugh2:

honesttjohn

· #6 · Apr 8, 2019 (Edited)

3

Gary,

On big projects like this one (37" across) I just brushed over the text with Zinser shellac and used acrylic paint, sanded, and stained.

On the smaller signs I use mask and acrylic paint - brushed on. Acrylic paint doesn't bleed much and sands right off. I've found that brushing instead of spraying, although more time consuming, leaves less to clean up, and looks better, especially in wood with rough grain. I've tried the Marsh Ink - but I think it looks like sprayed on ink.

Just my opinion. But I'm not paying anyone either, so time doesn't mean as much.

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Gary Wiant

Discussion Starter · #7 · Apr 8, 2019

Joat - your right not everyone but, but you are still basically doing the same thing. Paint it on & sand it off.

David & John I'll post a photo of what I've been using it may be sanding sealer & not sanding primer

difalkner

· #8 · Apr 8, 2019

This is about the only photo I have that shows something where I used Nitrocellulose sanding sealer and then brushed the letters and sprayed the apple. I don't see any bleeding in the photo and don't recall any when I did this.

Font Fruit Label Apple Plant

David

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harrysin

· #9 · Apr 8, 2019

As has been said, shellac is a perfect sealer, I wouldn't be without it.

JOAT

· #10 · Apr 8, 2019 (Edited)

Gary Wiant said:
Joat - your right not everyone but, but you are still basically doing the same thing. Paint it on & sand it off.

Nope, I do my sanding before painting, not after, just paint very carefully.

Gary Wiant

Discussion Starter · #11 · Apr 8, 2019

This is what I have been using. And I think I've figured out the issue.

This sanding sealer is water based & so is the paint ( krylon acrylic ) so I think the paint is "re-wetting" the sealer

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RJT501Win

· #12 · Apr 8, 2019

Hi Gary
When I am painting signs I either spray them with a clear finish or paint them (Particularly MDF) with a couple of coats of watered down Titebond. The Titebond on MDF does need a light sand if a smooth finish is required. Then I spray paint and sand as you do.
Cheers
John T

Pro4824

· #13 · Apr 8, 2019

It's the wood Gary! If you switch to bronze, the issue will go away. 😉

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gmedwards

· #14 · Apr 9, 2019

Gary Wiant said:
This is what I have been using. And I think I've figured out the issue.

This sanding sealer is water based & so is the paint ( krylon acrylic ) so I think the paint is "re-wetting" the sealer

Gary, the finish coat should not re-wet the sanding sealer, even if both are water based. I suppose it could happen if the sanding sealer was not allowed to dry enough before applying the paint, or there was something wrong with sealer. I've done tons of finish work over the years (including car and boat painting) and have never seen what you describe on a properly prepared surface and using the right materials. It could be your sanding sealer is too old, but I doubt that is the problem.

I'm not a fan of Minwax products. Varthane makes a decent product and is readily available. As others have noted, it's hard to beat dewaxed shellac. It's gotten harder to get fresh shellac these days, since Zinsser Bullseye stopped putting the mfg. date on the can. You can get shellac flakes at most woodworking stores (e.g., Woodcraft & Rockler) and dissolve/mix your own. Just be sure the flakes are dewaxed. I use shellac sealer under Sherwin Williams CAB clear lacquer and sometimes use it under their catalyzed lacquers (think white kitchen cabinets) (available at industrial sales only). Vinyl sealers are great, but they are pricey and can be hard to find. Sherwin Williams has one, but is spray application only It's a vinyl modified nitrocellulose product that doesn't have to be catalyzed, but should be for best performance.

For those who might not know, Zinsser Bullseye sealer is dewaxed. I don't use their regular shellac finish, but if memory serves, it is not dewaxed. Non-dewaxed shellac is designed as a finish, not as a sealer - even if you thin it with alcohol.

Gary

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Gary Wiant

Discussion Starter · #15 · Apr 9, 2019

My MinWax is new. At least I just purchased it, I guess it could have set at the lumber yard for a while. I let it set overnight and it felt dry. I ordered a qt. Deft laquer sanding sealer today. Hopefully it will work.

Thanks
Gary

gmedwards

· #16 · Apr 9, 2019

Gary Wiant said:
My MinWax is new. At least I just purchased it, I guess it could have set at the lumber yard for a while. I let it set overnight and it felt dry. I ordered a qt. Deft laquer sanding sealer today. Hopefully it will work.

Thanks
Gary

If the Minwax set overnight, it should have been plenty dry enough. Hard to say if it had just been on the shelf too long, or something else. Maybe it's just a bad formulation. Like I said, I'm not a Minwax fan.

I've never used the Deft sanding sealer. Not a fan of brushing lacquers. I've tried the Deft brush on finish once - it was on something small and I didn't want to clean my spray gun. I didn't like the result and tossed the can. IMO, lacquers are meant to be sprayed. I hope the Deft sanding sealer works for you. Let us all know how it turn out.

Gary

Gary Wiant

Discussion Starter · #17 · Apr 13, 2019

I tried the Deft laquer sanding sealer & it seemed to work great. I brushed on some craft acrylic and sanded it off very quickly with 220 grit on my orbital sander.

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