Pre-Raising the Grain -- Waste of Time?

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Jeremy Scuteri

Jeremy
Staff member
I came across this article and I thought it was interesting. http://askhlm.com/Home/HLMRedirect....id/75/ArticleId/28/Pre-Raising-The-Grain.aspx


One of the first finishes I tried was Boiled Linseed Oil followed by Shellac (wiped on using a heavily thinned cut). Later on I used Boiled Linseed Oil followed by General Finishes Arm-R-Seal and the result was a super smooth finish. I have done both of these a few times. I have noticed in hindsight that I didn't get any raising of the grain when doing this. I later tried a straight shellac finish (sprayed) and noticed that the grain raised with the first few coats. The current finish that I am doing is straight Arm-R-Seal and I am also noticing that the grain raised for the first several coats.

It seems that the initial coat of BLO really helps keep things smooth. Maybe this doesn't matter at all (which is what the article argues), but it is something that I didn't really realize until today. (This may be common knowledge to everyone else. In that case, just ignore this post) :)
 

Bill Clemmons

Bill
Corporate Member
Jeremy, I've been raising the grain on all my furniture projects for years. Is it necessary? I don't know. I guess it depends on the finish you use. When I need to 'color' wood, I prefer a water based dye. In that case, I think it is definitely advantageous.

If I don't color the wood, I go straight to a Varnish/BLO/Thinner blend. In that case, it probably isn't necessary.

When applying shellac, it doesn't seem to matter if you raise the grain or not. The first coat always seems to be a little 'fuzzy'. A light buffing w/ 320 paper brings it back to glass smooth.

One advantage I think raising the grain provides is a smoother surface, and less chance of hidden scratches that don't show up until after the first coat of finish.
 

CrealBilly

New User
Jeff
My opinion only on using any water based finish its a waste of time. My first and last experience with water based finish, I was taken by surprise. I spent much time sanding my piece. I loaded my spary gun with water based finish and hit it with one coat. Instant grain raise, needless to say I was pretty upset. I immediately cleaned that garbage out of my spray gun, threw away what was left and never looked back.

Nothing beats tested, tried and true oil based finish - I could care less about what gov has to say VOCs whatever that means... I just want a finish that works.

Maybe the Fountain of Youth isn't a fountain at all. Maybe it's a way of looking at things. A way of thinking.
 

merrill77

Master Scrap Maker
Chris
Never done it.

I generally don't use stain at all. I haven't tried a water-borne finish, yet. I've used water-borne dyes a few times, but didn't bother pre-raising then, either.
 

Jeremy Scuteri

Jeremy
Staff member
I haven't used any water based finishes, but I did get some General Finishes PolyAcrylic when Woodcraft went out of business. I haven't tried it yet, but I will in the near future. I really need to do some experimentation with some finishing techniques. So far, I just wing it on each project that I do.

Next project, I plan to take a few scrap pieces and try a few different finishing approaches.
 

golfdad

Co-director of Outreach
Dirk
Corporate Member
I get all my stain from Horizon Forest products and it is all non grain raising. Is this a mistake?......I have used a Trans Tint but only under a stai to keep the blotching down.
 

Jeremy Scuteri

Jeremy
Staff member
Is what a mistake? Buying that specific finish, the language used to describe it by the manufacturer or something else? If you have used it and you like it, it seems like that is all that should matter.
 

Jeff

New User
Jeff
A few guidelines that I've learned (mostly through reading) over the years about this topic. Basically, I don't worry about it and don't jump through hoops trying to fix it.

1. Water and anything containing it is a notorious grain raiser particularly after the first coat, but it's a once and done phenomenon. Lightly sand it back or do nothing and carry on? Your call. Try both and see if there's a noticeable difference in your hands.

2. Alcohols in general are considered to be non-grain raising (NGR) but some may occur with a given piece of wood and how it's been prepped.

3. Petroleum based solvents and finishes are NGR.

It can be called "finishing" the finish. As the microscopic surface builds with subsequent coats those initial fuzzy imperfections blend into the background so it may be much ado about nothing up front. :icon_scra
 

JeffH

Jeff
Senior User
I like to use water-based dyes because of their workability for fades and blending, and I do raise the grain before applying those -- largely because I can't sand after that step without removing the color I've just added. But everything else I use is oil-based, so after a barrier coat I can move ahead with sanding top coats to final smoothness. If I'm not using any dyes, I start with an oil-based blend and no grain raising is needed.
 

Jeremy Scuteri

Jeremy
Staff member
Howard, that is the same article that I posted above. Come to think of it, I think I found it from you on a different forum while doing some internet searching! Small world....


JeffH: The article addresses that situation (assuming what it says is actually true, which I have not verified myself). Here is an excerpt.

"My approach is a bit different—water raises the grain, so what! May I point out that the dye or stain step is only the first step (after sanding) in finishing the wood anyway; so, who gives a rip if the surface is a bit rough after the water step. You aren’t through yet! The only purpose of this step is to color the wood. I presume that you intend to sand between coats of whatever film forming finish you intend to apply. I also assume that you intend to apply more than one coat of your intended finish, whether water-borne, oil-based, or lacquer. Therefore, let those little (now colored) raised fibers stand there in all their rough glory. The first coat of your film forming finish will 1) seal the surface of the wood so that all subsequently applied finish is going to build on the surface, and 2) is going to lock the offending fibers in place so that they will easily be cut away by your first sanding—you know, the light sanding you are going to do when the first coat of finish is dry, in preparation for the second coat. Therefore, by the time you have applied and lightly sanded one or two coats (depending on the type of finish you use) all evidence of the raised grain is going to be gone anyway."
 

JeffH

Jeff
Senior User
I'll disagree a little with the article's position on that. I work a lot with high-gloss finishing using polyurethanes, and I can assure you that if you don't start with a smooth substrate you're going to have quite a battle trying to get a smooth topcoat. Those topcoat layers are intended (by the manufacturers) to be very thin or they can crack after they're fully cured. The idea of piling on thick enough applications to allow sanding out roughness of the substrate is erroneous unless you're using super-high solids materials like polyester or epoxy. At the very least, sanding the topcoat to try to level the lower coats can harm the coverage and evenness of the color.

This might not be as apparent if you're using dull finishes, particularly on open grain wood, but that doesn't mean it doesn't happen.

By raising the grain before applying dyes, the substrate can be sanded level before color and sealer are applied, and you can sand the top coat without having to literally sand through it trying to smooth the wood itself.
 

Jeremy Scuteri

Jeremy
Staff member
As I said, I haven't tried it, but I don't think the idea is to sand through your top coat trying to smooth the wood itself. My interpretation was that you are just cutting away whatever wood fibers are still standing above your 1st layer of topcoat, so you would just sand your 1st layer of topcoat like you normally would. It sounds like you have more experience with this than I do though, so you could be completely right. Have you ever tried skipping the pre grain raising step?
 

JeffH

Jeff
Senior User
Yep, I've tried skipping it -- just makes for more work later. Honestly, raising the grain and then smoothing with a light sanding is probably the quickest part of the whole process -- only takes a few minutes and not much energy. And, like folks have said, the question only comes up if you're using water-based materials.
 

Howard Acheson

New User
Howard
>>>> I don't think the idea is to sand through your top coat trying to smooth the wood itself.

You are correct. Apply a thin coat of your finish. This is enough to cause the shards to swell and then harden. Now lightly sand use 320 or 400 sandpaper. This cuts off the shards leaving a smooth surface.

I frequently use both gloss and non-gloss oil based and waterborne finish. I can say I have never encountered the problem Jeff H states.
 

Howard Acheson

New User
Howard
>>>> The idea of piling on thick enough applications to allow sanding out roughness of the substrate is erroneous

The issue is not an initial roughness with the substrate rather its the swelling of wood fibers as they load with finish. The loading with finish causes the fibers to swell and raise above the substrate surface and then harden causing roughness.

The technique is not a substitute for filling pores or flattening.
 

JeffH

Jeff
Senior User
The issue is not an initial roughness with the substrate rather its the swelling of wood fibers as they load with finish. The loading with finish causes the fibers to swell and raise above the substrate surface and then harden causing roughness.

Sorry, I guess I was unclear. The raised grain creates the roughness of the surface I was talking about. And it's due to the fibers swelling from water -- which is not the finish if you're using oil-based finish.

When you apply finish to raised grain, the finish coats those raised fibers as well as the original level of the wood. So when you sand it down at that point, you are in fact taking off finish when you take off the raised fibers. (By finish, I'm referring to varnishes, etc., that coat the surface but don't actually penetrate the way oil or water do, so it's not absorbed into the fibers but sits on top of them. The fibers don't poke through the finish -- the finish follows the shape of whatever is under it, fibers included.)

It really doesn't make a lot of difference (assuming you're going to apply more coats of finish) unless there's a water-based dye involved, because when you sand off the fibers you're also sanding off the color they carried and revealing fibers underneath that may not have as much dye saturation -- lightening the overall color in a similar fashion to changing the color/shade of selected pixels in a digital photo.

I wasn't referring to filling pores -- only about trying to get a level finish when the grain hasn't been pre-raised and then pre-leveled. Pore filling is a completely different issue.
 
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