Plywood finishing advice needed

[Kelly Colin Mark]

Hi everyone,

This is my first try at actually finishing a project. I am going to be building a shelving unit out of 3/4" maple ply.

I bought one quart each of:

1- "General Water based dye stain" (http://www.leevalley.com/en/wood/pag...,42942&p=64181) and
2- Satin "Enduro-Var Water-Based Varnish" (http://www.leevalley.com/en/wood/pag...,42942&p=67058).

I brushed the stain on a practice piece and let it sit for about a day. The color looked good. Then as per the varnish instructions, I brushed it on, let it cure for several hours, sanded with 320 grit with my Festool ETS 125 sander, and vacuumed up the dust. I noticed lots of scratches and scuffs as a result. I then repeated the above 3 more times (4 total).

The last time I sanded, I spent a lot more time on sanding to see if this would eliminate the sanding marks, basically until the whole surface was covered a layer of visible dust. Then I ran my orbital sander with fine and then very-fine polishing pads. This did eliminate the obvious sanding scuffs, but now I notice lines that look like scuffs. I can create identical marks by running my finger nail against the surface. Mostly these scuffs seem to run with the grain but some don't.

What am I doing wrong ? I'd expected by now that I would have at least a uniform-looking surface.

[Lee Mims]

I'm not nearly as skilled as the rest of these guys here, but one thing I learned quickly is that patience is the key to getting the superior finish. Once you put your topcoat on (poly, urethane, whatever), it needs to cure, and that takes 2 - 3 weeks, unless you're using some type of pre-catalized lacquer (2 - 3 days). Don't worry, you're not using that stuff, you'd know if you were, you can't find that stuff just anywhere.

I'd think the reason you have marks is that you attempted to rub out your finish while it was still curing, which is just gonna dig into the finish and leave those lines. I'd recommend putting on your stain, give it a day or two (try sniff test, to see if you smell the "stinky" coming off it....if you don't...it's ready). Put on a topcoat, and between coats of topcoat (usually 1 / day until it's where I want it, usually 3 coats), I hand sand w/ 320grit (first topcoat) and then 400grit (the following topcoats) just to knock off the nibs. Barely put pressure, all you wanna do is knock off the "mountains", you're not trying to sand it to the valleys, if you get my drift.

Then wait 3 weeks, and do what you were trying to do there.

Finishing is a waiting game, and rushing it has never got me the results I wanted. I learned to just set it aside and work on something else for a while and come back, and then my results starting getting "professional."

I'm sure someone who really understands this stuff will chime in soon.

Thanks for reading,
Lee

[Steve Schoene]

There are some steps you omitted in the description of what you did. First is the step where you wiped off all excess stain with a cloth or paper towel before it dried. Then you sanded the varnish after only a few hours, likely to be too soon. The companies instructions likely assume a mid 70s (degrees F.) temperature and 50% humidity. Any colder, (especially) or any more moist and needed time will be much longer. But in addition you used a ROS, when sanding between coats should only be done by hand with a sanding block. And ROS will always leave some cross grain scratches that show up clearly.

[John TenEyck]

I've used a lot of EnduroVar, but never GF's WB dye stain. However, it should have been plenty dry in 24 hours so I doubt it has anything to do with your problem. EnduroVar dries very quickly depending upon the temp. and RF, as mentioned, and can be recoated in just a few hours. You do not need and probably should not use a ROS to sand between coats. All that is need is a few gentle swipes with 320 grit on a sanding block. I actually prefer the thin 320 grit sanding sponges backed by a rubber block, especially on stained plywood which often isn't all that flat. I'll bet your ROS cut through the finish, and maybe the stain, too, on the high spots of the plywood leaving those ugly white scratches.

Try another sample. Do no more preparation than hand sand the plywood with 320 grit backed by a pad/block. Apply the stain and let dry overnight. Apply two coats of EnduroVar, letting it dry at least 4 hours between coats. Do not sand after the first coat. After the second coat has dried at least 4 hours, gently scuff sand with 320 or 400 grit with a felt of rubber backing block. All you want to do is knock off any dust nibs; you are not trying to level or sand the finish in any other way. Vacuum and wipe off the surface with a microfiber cloth, then apply another coat of EnduroVar. When that has dried it should look and feel very good. If it still needs another coat, lightly scuff sand again, clean, and apply another coat. If that doesn't meet your expectations, somethings really wrong.

This is what EnduroVar looks like with no rubbing, etc. It was done just as I described above.

IMG_9465.JPG



John

[Kelly Colin Mark]

Thanks everyone for your replies. I've started again on another piece of scrap.

I brushed on stain then, as Steve suggested, wiped off all excess. Waited about 3 days - checked that it doesn't smell as Lee suggested. Today I bought a sponge paint brush/pad and applied the first coat of EnduroVar.

I'm going to let it sit for a good # of hours - maybe 7 or 8 - before I do my second coat. Will not sand before that.

John - that picture looks lovely. Just laying on coats of the EnduroVar got you there - no other finishes or wax ? If I could get halfway there, I'd be thrilled.

[Kelly Colin Mark]

I've got my second coat drying, but have two questions:
1) the General Finishes videos usually show the people applying the stain or varnish with a foam brush. Is there a reason to prefer foam brushes over bristle brushes ?

2) Is there a reason to stir the stain or varnish, instead of shaking up the can ? The instructions and videos all seem to show stirring and not shaking.

thanks !

[Scott Holmes]

Many believe that shaking introduces too many bubbles in the varnish or finish. FYI - water borne finishes are not really varnish as in oil-based varnish they also don't cure like a varnish they are coalescing finishes.

I shake varnish an WB finishes all the time; proper thinning and application techniques will eliminate the bubbles. Many people cause more bubbles then shaking by dragging their brush across the of the can.

[Kelly Colin Mark]

Thanks Scott. I saw your video in the sticky and found it quite informative and helpful - thank you.

But am I correct that some of the brush care prescriptions - e.g. mineral spirits - aren't important for use of water-based products ?

[Scott Holmes]

You still need to follow the same prep; but, you will use water to condition the bush, instead of mineral spirits. Clean up can start with acetone or ammonia or just soap and water. I normally use soap and water, it's much cheaper.