What are the advantages of priming wood before painting with a conversion varnish?

I have read and been told the conversion varnish is a self sealing product.

Thoughts?

Mark

The major problem with cv is film thickness. Exceed it and you may get cracking.

Painting takes more coats than clears. Typically you prime and all of the defects pop out. You fill them and sand the primer & filler at the same time. You then lay down 2 coats of cv.

When doing high gloss work on cabinets or furniture that have lots of brad holes and other defects, it’s common to do 2 prime coats and 2 topcoats.

I do 2 coats of primer and one top coat .I find the primer drys much faster and sands easier than top coat .
Also if I'm painting any color other than white or off white I'll have the primer tinted to match the top coat .

If you have a good Conversion varnish, and skilled sprayers, you can definitely spray self-sealed.

We've done it since 2013. Two coats opaque CV and one coat of clear.

This is also very similar to what Conestoga does. Their CV (which you can buy) behaves like a topcoat/primer mix. It isn't quite a powdery feeling as a primer but way too dull to be left as a final coat. I'm pretty sure all they do is 2 coats of opaque, 1 coat color.

Skipping the primer benefits in a number of ways. I'm spraying only 2 coats of opaque rather than 3. No primer to purchase/stock/inventory.

And you can use "similar" colors that are leftovers as the undercoater for others, as long as you don't go to far off the tracks in terms of color difference.

If you want a flawless paint job then priming is what you need to do. Your end result with finishing is all about your prep work.... If you put thought/effort into building your pieces with great care... prep well and fill defects/seams well your end result will show a higher quality result. With C.V our process is actually to build C.V. based primers wet on wet... mulitple coats with flash times between coats while still in the booth... thus building the primer coats past what would be considered 5-6 mils when dry..... That way after the primers cures we sand the primer back hard to level the finish and thus covering any seams or open grain.... Once that is prepped completely one topcoat of C.V. yields a perfect finish..... Do all the hard work before topcoat!.. Sanding back primer is much more effecient than sanding topcoats because you didnt get it right the first time

Advantages of primer:
easier to get great finish by filling defects and easier sanding (which works out to better finishing in most cases due to the human effect).
Advantages of no primer: harder finish quicker as the primer is softer than the CV. Usually this is not a problem unless you are stacking, shipping say a pallet of doors. Probably would not be an issue for most. No inventory of primer and switching/cleaning guns in between.

First of all, I appreciate the comments left in regards to my post. Most helpful.

Matt, I like your argument for using left over similar colors to use as a seal coat.

I sprayed a bunch of doors today and used primer. Am getting very good results. The next job, I may use CV and see how I like those results.

I'm using 2 pumps for my paint. For primer I'm spraying SW Gen 2 Universal water based primer, then the second pump for my solvent based finishes.

The only issues I'm having with the primer is it dries up on the tip and I have to fight to keep it clear in order to lay down a nice coat. That's what got me thinking about using the CV as a seal coat.

I do appreciate the thoughtful and reasoned comments by all.

Mark

If you insist on using the waterbased primer then think about keeping a pail of water and stiff brush right at your spray area.... after spraying a setup and you see some build up use the brush to keep cap and tip clean... Ideally your build up on tip should be faint or you may be using the wrong tip size for the atomization of your material.. if so you need to go up a size and adjust accordingly....
Another note.... sanding topcoat smooth is a totally different animal than sanding primer.... If I was a prep guy sanding your stuff I'd be cursing you for handing me topcoat to sand as primer... i't does not powder up as well.... Definitely not apples to apples in effort.... or appearance .. Topcoat is generally not designed to fill..It's designed to meet your sheen needs and hardness needs for protection.

Shane,

I hear what you are saying about sanding primer vs top coat as a sealer coat.

I still want to do at least one small job using my CV as a sealer coat so I can see and feel the difference for myself. There is some merit to using left over comparable colors as a sealer coat to use up the material. I have to buy a gallon at a time for my CV, and I would rather spray it out then let it sit on a shelf too long.

I have been using a 411 tip for my primer. I'm going to try a 413 and cut the fluid pressure back a bit to see if that doesn't help with the build up on the tip.

Your advice is appreciated,

Mark

I agree with both sides here on the advantages and disadvantages of using primer over self seal topcoats or enamels. It really matters what the scope of the job is. In ceiling and wall systems you can get by with a self sealing product, if its furniture or kitchen cabinets a primer should be used.

Ease of sanding is not the big issue in my mind. Most cv’s are easy to sand. They are designed to be.

The problem that I am always concerned about is the difference in hardness between the coating and fillers. The hardness has to be very close or you get telegraphing thru the topcoat. We have a spackle type filler that matches our primer in hardness. We don’t fill the wood or ply. We put down the primer and fill all of the defects.