Priming Baltic Birch Plywood for Paint

Advice on a heavy-bodied primer that won't raise the grain of birch plywood. January 29, 2009

I'm trying to get my half inch baltic birch primed for painting and have experienced no end of frustration. I have read a few posts on the subject and most of them were suggesting to use MDF instead. This isn't an option for me as I need the structural integrity of the plywood for edge screwing - where MDF would just break away.

I know it's very low tech but I've rolled on two layers of Kilz - thinking I'd just sand them down level with the grain - and that didn't do anything to hide the grain. It just made it much worse in fact, so then I applied a layer of Bondo on top figuring that would definitely do it. A very thin layer didn't do anything (maybe I need to thin it down) and a thicker layer is impossible to sand evenly with a random orbital. Can anyone think of any magic bullets to do in this case? Would a layer of thinned wood glue work?

Forum Responses
(Finishing Forum)
From contributor R:
Im not sure what your intended project is but is there any way you can just pour on the primer and let it level itself? It might take a few days for the primer to dry as it depends on how thick it is. Once its dry you can cut it down with a belt sander and an aggressive grit belt, say 100 or 120.

From contributor H:
You may want to try some Evercoat Featherfill or ML Campbell Clawlock primer.

From contributor A:
Kilz is an "off the shelf" primer designed for brushing not sanding. You need what is referred to as an undercoater/surfacer. These are very high solid paints that sand easier than drywall compound. These are pro grade products that you won't find at the hardware store. You should be able to get some at Sherwin Williams.

From contributor E:
Rodda makes a white wood surfacer that is a very high solid primer. I use to seal edges on MDF so they don't absorb my topcoat. I prefer spraying, but pouring or brushing on heavily should work just as well. This product also sands extremely well since it is a vinyl base.

From contributor O:
Contributor A is right I think. When the customer wants to paint themselves or use a painter I spray them with SW sandable primer. It's quick, easy, and effective. Plus, a sandable primer leaves a smoother surface for topcoat. If youre trying to completely obscure the grain I would try a thinned waterbased wood filler or metal.

From the original questioner:
I guess most of these can't really help me this time around since I doubt it would really work on top of the Kilz (unless that's what you're suggesting). Buying new sheets is just not an option. If I were to be able to start from scratch I'd have tried the Clawlock or else some epoxy paint. But there's no turning back the clock I guess so I'm just going to do a few more layers of the Kilz with no sanding. Im thinking that it's the exposing of the grain during sanding with water based primer on top of that that's causing the problem.

From contributor G:
Of course you can put other products over Kilz - that's what it's for. Do you have access to an industrial coatings distributor? If so, ask them for heavy-bodied primer. The aforementioned Clawlock will work just fine. You can also get something that will work at the auto-body supply shop.

From the original questioner:
Yeah - I just figured that you want the Clawlock to bond with the wood, and putting it over Kilz might be kind of moot.

From contributor S:
I've been spraying Insl-X Aqua Lock for quite some time now. Works great as a sealer and after second coat sanding the topcoat goes on very smooth. I'm about to paint a set of birch cabinets with MDF doors.

From contributor M:
I always use denatured alcohol for thinning and clean up - the ammonia thing is smelly and unnecessary unless you dont have any D.A. on hand. You didn't state what size your panels are, but if i didn't have spray equipment Id just use a short nap 6" "weenie" roller.

The object is to get it on as quickly as possible - less is more - as in as few passes with the roller as possible to get an even wet coat. Do not go back over it at all. Just roll and leave it alone. It will flow out and level off somewhat. When dry sand as needed and go from there.