Crystallac over Shellac?

[JoshK]

I read the online instructions for Crystalac and prior posts here, but am wanting to confirm that you can use Crystalac over Shellac. I was thinking of putting a Crystallac finish over the top of the Shellac for a more durable finish.

Does it have any problem bonding? Should I "scuff" the shellac (w/ 320) before Crystalac application?

[Jim Holtz]

I read the online instructions for Crystalac and prior posts here, but am wanting to confirm that you can use Crystalac over Shellac. I was thinking of putting a Crystallac finish over the top of the Shellac for a more durable finish.

Does it have any problem bonding? Should I "scuff" the shellac (w/ 320) before Crystalac application?

Hi Josh,

I'm no Crystalac expert but I think it'll be fine. I'd suggest you scuff it lightly before coating with Crystalac and try it on a scrape piece to make sure. My experience with shellac has been that you can use about anything on top of it once it's dried.

HTH

Jim

[Bill Schneider]

I'd stick with dewaxed shellac to increase adhesion. There are some differences of opinion about the need for dewaxed shellac, but I'd rather be safe than sorry.

Here's a thread I found discussing dewaxed shellac under other coatings...

http://www.woodweb.com/knowledge_base/Regular_or_dewaxed_shellac.html

[Curly Woods]

I read the online instructions for Crystalac and prior posts here, but am wanting to confirm that you can use Crystalac over Shellac. I was thinking of putting a Crystallac finish over the top of the Shellac for a more durable finish.

Does it have any problem bonding? Should I "scuff" the shellac (w/ 320) before Crystalac application?

Zinnser "SealCoat" is a dewaxed shellac, They also have another type that is available in clear and amber tints that is also a dewaxed product ready mixed. if you don't want to bother with mixing your own from flakes. You can coat over it with any finishes that I am aware of without issue.

[Lurkalot]

I echo Jim Holtz's comments about shellac being a suitable sealer for a myriad of topcoats. It was (and still is) used as a sealer under conventional nitrocellulose lacquer, and I have applied enamel, latex and alkyd-base paints over it.

Finishes bond via both a chemical and a physical connection with the substrate, so scuffing any the surface prior to the initial top coat application is good advice.

Happy finishing!

[JonP]

Yep, the general consensus is that Shellac (dewaxed) is one of the most compatible of finishes. There's supposed to be nearly nothing that you can't put over it. I'm not sure if the "regular" (non Seal Coat) Zinnser Shellac products are truly dewaxed, thought they weren't... but using Seal Coat you'd be sure.

I'm kind of wondering about the scuffing... yes it generally would improve the mechanical bonding, but I'm wondering if it would cloud the surface slightly... Perhaps the wetting of the second finishing substance would eliminate that, or maybe it wouldn't. OTOH, maybe its not needed for a solid coat. I'm not an expert, so the best way to know applies... try it out on some test pieces and see how it goes!

I agree with some kind of more durable coat... I have a pair of Modula MT's with a total OCD, 20 or so coats, of just Zinnser's Seal Coat over Mahogany... beautiful, deep, glowing grain figure... and if you bang it with something, it dings easily.

Doing it again, I'd do a much thinner layer of Shellac, then build up with some Poly or something for protection.

[Curly Woods]

I'm not sure if the "regular" (non Seal Coat) Zinnser Shellac products are truly dewaxed, thought they weren't... but using Seal Coat you'd be sure.

You are correct Zinnser's "Bull's Eye" Shellac, is not stated to be "wax-free", as the Seal Coat is on the their web site. Seal Coat can be used alone as a top finish also.
The great thing about shellac is it will not yellow like oil based finishes do over time and it is a natural UV protective finish also.

[JoshK]

I was using standard (I think) Zinnser Shellac, bought from the big box.

I like working with Shellac and prior success gave me confidence to use it. I like how the end product looks, but was thinking that a more durable finish would be a good idea for the topcoat, hence the idea to use Crystalac.

I have a large compressor, but it is too cold to spray outside, so maybe I should get the brush on type? Is it too noxious to use in the basement? I can open the windows in the basement but there is still limited air flow.

Otherwise, I will make due with the Shellac finish until warmer weather in the spring and then spray the final coat(s).

[Jim Holtz]

I was using standard (I think) Zinnser Shellac, bought from the big box.

I like working with Shellac and prior success gave me confidence to use it. I like how the end product looks, but was thinking that a more durable finish would be a good idea for the topcoat, hence the idea to use Crystalac.

I have a large compressor, but it is too cold to spray outside, so maybe I should get the brush on type? Is it too noxious to use in the basement? I can open the windows in the basement but there is still limited air flow.

Otherwise, I will make due with the Shellac finish until warmer weather in the spring and then spray the final coat(s).

Hi Josh,

I love Crystalac! :T It has almost zero VOC's. There isn't hardly any odor at all and clean up is a breeze. However, the only Crystalac products that are brushable are standard Crystalac which has a slight amber tint to mimic shellac or poly which I think is close to water clear. I've used a lot of the water clear super premium and I just bought a quart of poly to refinish a door that has some weather damage.

It dries super hard and is extremely durable. Cool stuff!

Jim

[numberoneoppa]

Jim, I can't tell, are you saying that the Super Premium is or is not brushable from your experience? I've been planning on picking up a can to finish my North Seas.

[Jim Holtz]

Jim, I can't tell, are you saying that the Super Premium is or is not brushable from your experience? I've been planning on picking up a can to finish my North Seas.

Based on Crystalac's recommendations here's a list:

Premium - spray or brush
Super Premium - spray only
Solid color (white or black) - spray only
Poly - spray or brush

I've used Super Premium and the solid color on various speaker builds and have played with poly. I sprayed Super premium and solid but brushed the poly. All lay down extremely smooth. When you're spraying or brushing, it doesn't look like it's flowing out like regular paint or top coats do. However, if you walk away for about 10 minutes, it'll be glassy smooth when you come back and dry to the touch in 10-15 minutes. Recoat in 30 - 60 minutes. Poly is a little longer if I remember correctly.

Jim

[numberoneoppa]

Thanks, Jim. =)

[JoshK]

Just as a follow up, I did brush the Premium grade of Crystalac over the shellac. Works like a charm and the finish came out very nice.

For those who have used Crystalac before, how do you suggest polishing it out when done? That is the step I am at and plan to finish it up this weekend.

[Jim Holtz]

Just as a follow up, I did brush the Premium grade of Crystalac over the shellac. Works like a charm and the finish came out very nice.

For those who have used Crystalac before, how do you suggest polishing it out when done? That is the step I am at and plan to finish it up this weekend.

Hi Josh,

Here's what I've done. I treat Crystalac just like lacquer. I let it cure 3-7 days (longer the better) and then sand lightly with 800 - 1000 grit sandpaper. I follow up with 1500 and then do a final sanding with 2000. It should be a satin looking finish at that point.

I use 3M ultra fine buffing compound designed to be used for automotive clear coat finishes and buff with an automotive style buffer. I then follow up with 3M swirl remover.You may not have the same equipment available that I have. I used to be a car dealer many, many years ago and had a body/clean up shop. I've kept the tools even though I infrequently use them.

Crystalac polishes like automotive paint and will buff to a mirror finish.

Jim

[numberoneoppa]

Let's not forget to always apply crystalac in a room that is over 70 degrees in temperature or it won't smooth out. I tried doing it right at 55 (minimum allowed) and it just doesn't work well because it's water-based.