Vinyl Sealer Versus Regular Sanding Sealer

What's the difference, and why does it matter? Top pros weigh in. July 3, 2008

Can someone tell me what the difference between vinyl sealer and regular sanding sealer is? Can I use vinyl sealer instead of primer, and can I use vinyl with pre-cat lacquer or regular lacquer? I what to paint a cabinet with white lacquer paint on MDF panel and I want to make sure vinyl sealer is good for this.

Forum Responses
(Finishing Forum)
The vinyl sealer has better water resistant properties. I don't know the answers to the other questions. I usually self seal or use a primer for leveling purposes.

From contributor J:
Read the product data sheet for your topcoat. It will have recommendations whether to self-seal or what an appropriate sealer is.

From contributor C:
Your vinyl’s are normally a copolymer of vinyl chloride/vinyl acetate. Sometimes they are offered as a nitro/vinyl mixture for quicker drying and increased hardness. Some are also made with sanding aids for easier sanding, but not as easy as nitro sanding sealer. In use under nitro lacquer/acrylic/or other evaporative finishes they give increased water resistance and are normally recommended for such purposes by the KCMA when used there or in other high humidity/wet areas.

If used under cat finishes it is recommended to use a type that is copolymerized with a small amount of alkyd amino resins because the acid catalyst may attack a non catalyzed vinyl sealer. Many times it is also used for first and inter-coat adhesion needs when applying glaze and other color affects.

SW has a white vinyl sealer that would probably be a good choice as a first or second coat for you to use before you apply the white lacquer. This will help with the opacity you may need to achieve on your project. Also keep in mind that nitro white will yellow in time. If this is not wanted then you may use cab acrylic in its place. SW has a cat version of their cat clear for this if you'd like to check it out. Also keep in mind vinyl sealers do not sand easily as nitro's do and if the extra water resistance is not necessary for you, you may want to stick to your sanding sealer instead for ease of leveling your coatings.

From contributor C:
You can use any cat primer for edges, although the primers and top coats may be water resistant. None are "waterproof" though most all are good enough for above the waterline applications. The need to prime MDF on the main surfaces is by choice. The better grades really don’t need this but you can do if you want.

From contributor P:
Q. - What's the difference between vinyl sealer and sanding sealer?
A. - Vinyl sealer has better moisture resistance than lacquer sanding sealer. Vinyl sealer has excellent adhesion properties and is often specified as a pre- and post layer for glazes in a catalyzed finish system. Vinyl sealer is not as easy to sand as sanding sealer and depending on the brand it can be difficult to sand. Sanding sealer's claim to fame is how nicely it sands to form a smooth, flat base for the topcoats.

Q. - Can I use vinyl sealer instead of primer?
A. - Why would you want to?

Q. - Can vinyl sealer be used with catalyzed lacquer and non-catalyzed lacquer?
A. - Yes.

Q. - I want to paint a cabinet with white lacquer paint on MDF panel is vinyl sealer good for this?
A. - Vinyl sealer won't give you any fill on cut or routed edges like primer will but it will seal the surfaces.