Blankstock 201: The Finer Points of Blankstock
 It's been a while since we wrote anything about blankstock, which is clearly the main ingredient in showroom-type paperhanging. When it comes to knowledge about blankstock, people can be divided into four camps.
1. those who have never heard of it
2. those who misunderstand it
3. those who understand it, but choose not to use it, and
4. those who use it every chance they get.
We hope to move more people to the last category. Not only will more sales of blankstock fatten our bank account and delight our college-age daughter, who always needs more money (for shoes). It will also improve the industry because more fine wallpaper installations will look their absolute best!
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Here's the 101 description of blankstock:
Blankstock lining paper is a traditional product used under fine wallcoverings to absorb excess moisture from the finish wallpaper. It allows seams to dry sooner and safer, and promotes short-term stability of the installation (10-20 years). The functions of blankstock are similar to those of an underlayment for carpet or a lining for a curtain or drape.
Blankstock can be dispensed with for most mass-market wallcoverings, but fine wallcoverings such as handprints, blockprints and unpasted European machine prints benefit from an installation over blankstock lining paper.
Let's expand on this basic definition.
First, none of the functions of blankstock include "smoothing out the wall". Blankstock is a skin. If you have a small bump or sheetrock nail divot on your wall, and put blankstock on it, you will then have a wall with a blankstocked bump or divot.
However, blankstocking does result in a "softer", more uniform wall. It's a great way to get away from hack paint jobs with visible brushstrokes. Also, some rooms have strong color contrasts which might show through flimsy finish papers.
Fine paper hung on a painted wall often rides the wall a little hard. It may look fine in the sample book and while going up, but once it dries, it may show more of the wall than you like.
It takes a fine eye to determine what will show through, and what won't. We agree that "you never do exactly the right amount of prep: it's always too much, or too little". Naturally we are in the "too much" camp. We believe that when the stakes are so high, it would be foolish to take a chance on something showing through and spoiling the installation.
Sometimes a paint film looks a little suspect, but doesn't seem to call for the ordeal of oil-base priming. In that situation, blankstock could be a good choice, because if anything goes wrong, and a few seams pop, they can be quickly repaired. This is far better than if they pop under the finish paper, which would be a nightmare.
The 101 description says blankstock is good for "10 to 20 years" because like all pulp or groundwood stock paper, it's acidic. This means that it yellows with age and becomes brittle, like newsprint. This is not a problem for most decorating uses, but if you're hanging a "legacy" type product such as a French or Chinese scenic, you might want to offer your customers a liner upgrade. That would be acidfree liner. Acidfree is about 4 times more expensive than blankstock, but it's a real professional upgrade because it's a rag paper that will last at least 100 years. That's a long time. Not only plenty of time for the check to clear, but time enough for several more generations to enjoy your work.
The products of the Ampersand companies (Cowtan & Tout, Osborne & Little, Colefax & Fowler, etc.) are good candidates for blankstock because they're paper products that handle quite differently from most American papers. They can be hung with clear premix directly to a painted wall but because the adhesion may not be the greatest, the seams have a tendency to get beaten up during installation. If the seams are rolled hard and washed repeatedly, they can easily get bloated as the paper fibers fill up with water. Once the seams are saturated, the inks have a tendency to wear a little, leaving white or discolored seams.
These various seam symptoms are in addition to the fact that paper hung on painted walls is liable to contract, leaving a slight gap, for the simple reason that the paper started contracting while the adhesive was still wet.
 In the bad old days Britpulps would blush and sometimes even stain if blankstock wasn't used - the excess moisture could sometimes percolate through and affect the face of the wallpaper. Staining (strike-through) rarely occurs these days because the paper stock, inks and coatings of Britpulps are more durable now. So, blankstock is not quite so important as it used to be. Still, there is no doubt that blankstocking for traditional papers results in an easier, safer and more predictable installation.
We compare blankstock to an underlayment for carpet and a liner for drapes because it's one of the finer things of life. Yes, you can usually do without it. But do you really want to do less prep for an installation which can easily cost a thousand dollars or more, and is usually done in beautiful and costly surroundings? Why not pull out all the stops and do the best job possible? Cheapo decorators often pressure paperhangers to do without blankstock because it keeps prices low. Customers can be difficult to persuade, because they're usually unfamiliar with the difference that a liner makes.
That leaves paperhangers on the firing line. As part of your professional practice, you should insist on the right prep using the right ingredients. That's why we consider objections to using blankstock as teaching opportunities. When your gut says "better use blankstock", tell them that you need to use it, and explain why. You may be surprised at their positive reaction.
It's easy to justify "saving money" by not blankstocking. But it's hard to forget an installation that doesn't look quite right - especially when you know the reason why.
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The Seam Cycle
What is it? The seam cycle is the time between installation and the best time to roll the seam.
For most wallpaper, this is a wide space of time. Blankstock helps to shorten the time considerably. Why is this a good thing? Because having a wide space of time to roll the seam can be confusing. A seam rolled too early, or too late, is often a bad seam.
If the seam is rolled early - even a little early - it may separate because the paper naturally continues to contract until the paste is dry. If the seam is rolled too late, you're screwed. It's not going to get any better! So, the tighter the time frame, the easier it is to keep track, and the more likely it is that you can find that "sweet spot" when the seam can be rolled to perfection.
Let's look at a typical Britpulp paper installation on blankstock. The paste is wheat paste, cellulose, or a combination of the two. The strip is pasted, and sits for five minutes. The strip is double-pasted to spread the paste evenly, booked, and soon brought to the wall. The strip is unfurled, and placed about a sixteenth of an inch from the preceding strip, swept out, and trimmed top and bottom.
Next, the seam is closed up to a butt seam, about 6 inches at a time, by pushing the whole side of the paper (not just the seam area). Usually it can be rolled lightly, to seat the paste uniformly.
Now the "seam cycle" clock starts ticking, as the paste begins to sink into the blankstock. It's a good idea to time the first few strips to find out what's happening. Runner's watches and cell phones with stopwatch functions make this relatively painless. What happens next depends on the type of sizing, paper and type of paste. A starchy paste on a clay-sized blankstock with really porous paper will set up quickly and should be rolled right away. But cellulose-type pastes or pastes with a booster of clear premix, especially when used with coated paper, may take as long as 20 minutes to sink into the blankstock.
The important thing is to roll after the time when the seam will stay put, but before the time when it will be locked down forever. Small adjustments to the seam are often necessary. Really small adjustments, such as pulling a wired seam back, or bringing a scalloped seam together. Walls are not flat, and pretrimming is not perfect.
When the seam has been adjusted, the last step is to nail the seam. Going through the adjustment phase and checking out the whole seam usually gives you an idea of when to make a move. It's best to use a wide seam roller because you want to lay the whole seam area down, not just the seam itself. It's also best to keep a sponge handy, because paste often oozes out unpredictably. If the paper is sensitive, sometimes it's best to roll the seam a bit later, and without any washing. You can always go back and wash and pat dry later, if needed.
Often a seam can be made better by adjusting the previous strip as well as the one you're working on. This because the previous one, having set up much longer, moves less than the current strip. If you always adjust the current strip to the previous one, the current one may contract later and pull back a bit. If this is happening consistently, try adjusting the previous strip to the current one. The way to do this is to roll the current strip to not quite a butt seam, wash, then push the previous strip over to meet the current one.
Ideally, you should be able to move both previous and current strip a little, just prior to setting the seam. In this way you get the best adjustment possible, instead of leaving just one strip to do all the moving. This requires a high degree of control and is another example of why blankstock is so helpful to getting the "perfect seam" that we all want.
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Getting a great seam is all about control. Nowhere is this more important than with blockprints. We try to be broadminded when discussing blankstock, but if you're thinking about hanging the following types without blankstock, you need to think again: Adelphi, Zuber, D'Offard, Mauny, Gracie, De Gournay, and some Coles. These are likely to be printed with water-sensitive colors, and one bit of paste on them can become a permanent problem.
When taking these products to the wall, it's best to go right to a butt seam. Don't roll it, just get it butt, or nearly so, but never over the edge. A two-inch piece of wax paper across the width of the paper at top is very effective at keeping the cornice or ceiling free of paste. After the strip is trimmed, wash the woodwork by holding a broadknife against the paper to protect it and swiping the baseboard with a sponge. After washing the trim, be sure to dry hands completely with a towel. Now the seam can be prodded gently into shape.
It's best to try for a slight wire, in other words, you want to create a slight "tenting" effect at the seam. This is because there's always some contraction as the seam area dries, even though the pasting may be minimal. An initial wait time of about five minutes is advised. If the paper isn't against the wall, the paste may be drying out because of exposure to air. So get it flush to the wall as soon as possible. Usually fingertip pressure is all that's needed.
While concentrating on the seam in front of you, don't forget to put the other edge down. This is best done with fingertip pressure, to be rolled later by a seam roller when safe to do so.
When seam rolling begins, do it very gently. At the first sign of paste, ease off. Do something else, but return to the seam every five minutes or so, until it's ready to roll firmly without any, we repeat, any, paste coming through the seam. This can take quite a while, so be patient. If you don't want to be patient, don't be a paperhanger.
Under ideal conditions, you now have a perfectly butted seam with a slight wire. The final step is to return when it's safe to do so and roll tightly, pushing the wire until it disappears. Do not overdo it.
This may take a little experimenting with each side of a seam roller, or, with a beveled seam roller. A blockprinted seam is exactly ready to roll when it's exactly ready to roll. There are no rules. But, being able to work it all out, so that you know how to make those seams disappear right on schedule, is what masterful professional paperhanging is all about.
10 REASONS WHY BLANKSTOCK MAKES YOUR LIFE MORE FUN
1. - after a paste size, multiple seam layouts on blankstock can be penciled in, and the marks easily removed with a swipe of a sponge.
2. - seams can be rolled and finished much sooner, usually within 15 minutes - as opposed to over an hour, or longer, when working directly on a painted wall.
3. - allows the use of less aggressive pastes, resulting in easier and more thorough cleaning.
4. - use of less aggressive pastes (powder pastes), such as cellulose and wheat, are way easier to lug around and way easier to keep fresh because you mix only what you need.
5. - usually eliminates the need for extra steps like a reinforcing band of paste on the wall (Velcro effect) for difficult-to-seam materials.
6. - installing blankstock is a "trial run"; you get to know the room better, resulting in better seam placement for the finish paper; also, gives you a closer look at woodwork and inside corners which might need caulking, and out-of-plumb outside corners which might need fancy adjustments.
7. - allows very precise positioning for silks and touchy papers such as blockprints, textiles and weirdo "designer inspirations". For example, it's very easy to draw a grid on blankstock for installing handmade papers.
8. - removing and replacing a bad strip from blankstock is much easier than from a painted wall, and the replacement piece locks into place much easier.
9. - allows you to adjust the size to fit the finish paper, ranging from no size to a conventional paste size to a very aggressive clay size which will grab like crazy. Good proportion for a clay size is 20% clay, 80% cellulose.
10. - you get to answer comments like: "What is that, a backer paper?", "I like this color! Maybe I'll leave it up!" and "Why are you doing that?" Okay, maybe that's not fun, but I needed 10 reasons.
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