Flatening hardboard?

Page 1 of 2  
After I built my workbench, I made it so I could use a 36" x 72" piece of hardboard drop in, being able to change it out when necessary. Unfortunately, the sheet I had on hand had been leaning against the wall with something behind it, making it quite uneven. After cutting it to size it will not lay flat.
Does anyone have any idea as to how I might be able to get it to lay flat again, without gluing down? Is that even possible?
Any ideas is much appreciated!
markndawoods
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Sometimes gravity is your friend here. Other times it's just not fast enough.
Hardboard is a pressed paper board that does survive getting wet reasonably well. You might try a combination of gentle heat and moisture to get it to flatten out a bit. (Leave it out in the driveway, turning often?)
You might try a temporary spray adhesive, but sometimes temporary adhesives become quite permanent after several months.
Puckdropper
--
"The potential difference between the top and bottom of a tree is the
reason why all trees have to be grounded..." -- Bored Borg on
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Puckdropper <puckdropper(at)yahoo(dot)com> wrote in

You might also try lightly wetting (damp sponge) the concave side, then putting the piece on the table convex side up and weighting it down. It cups because of the difference in moisture content between the two faces.
8d nails every 4 inches on the edges and every 6 inches in the field will also be effective, if you're in a rush ;o)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Markndawoods wrote:

Eight bucks and a trip to the lumber store. :-)
--

-MIKE-

"Playing is not something I do at night, it's my function in life"
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 27 Jun 2009 17:03:51 -0700, "Markndawoods"

Dampen it and weight it down.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I thought of that, but was afraid to put any moisture to HB, thinking I would end up with a flaked or a powder top before it was all over with!
I will cautiously try this approach.
Thanks for everyone's input.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I got a couple pieces of tempered hardboard wet last winter while fighting a bulge on the ice rink. (Woodworking tip: Sometimes it's not the size of your fastener, it's the location of your fastener.) There was minimal swelling, and it went back to normal size.
It's not like the compressed sawdust product that crumbles when it gets wet.
Puckdropper
--
"The potential difference between the top and bottom of a tree is the
reason why all trees have to be grounded..." -- Bored Borg on
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 27 Jun 2009 17:03:51 -0700, "Markndawoods"

Definitely possible. As others have indicated, moisture will do it. You didn't say whether it was tempered or not, and I'm not sure that would make a difference, anyway.
I built a mantle for a while back, and the part between the shelf and the top of the firebox was filled in with some thin sheets of oak. Too thin to tongue and groove so I decided to back them with hardboard. Used PVA glue to laminate them and the moisture content of the glue durn near caused the assembly to bow into a circle. Don't remember now which direction it bowed, but moisture will definitely cause it to move, or straighten out if you guess right on which side to dampen.
Tom Veatch Wichita, KS USA
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'd be inclined to put it down with contact cement around the edges with a few dabs in the field. I've never been happy with loose hard board tops as they always seem to be loose--at least they feel that way compared to working on solid maple or solid plywood. The contact cement can be loosened with heat if it doesn't peel off easily at replacement time.
John
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Markndawoods" wrote:

Bricks and/or concrete blocks for weight and patience on your part.
Weight it down, wait 30 days minimum.
Lew
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Markndawoods wrote:

doubleback tape and a harborfreight 18 ga brad gun does the job - just a few brads around the perimeter until it lays flat.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Many years ago, in my youth and innocence - try anything once style, I bent some perforated hardboard round a former to make a dirty-linen chest - obviously tricky because it would prefer to bend along the lines of the holes.
I managed it by plying a steam jet to both sides of the board while coaxing it round a frame.
This makes me wonder whether a domestic steam laundry iron might do the job of flattening this area?
Jeff
--
Jeff Gorman, West Yorkshire, UK
email : Username is amgron
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Just try setting it out on a flat surface in dirrect sun light on a hot afternoon.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

You can try laying it on the lawn in the sun. Place the board like a coffee cup that is upsidedown. The warm moisture underneath should expand that side. I have used this method with doors and it works 80% of the time. For you application I'd use carpet tape too.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Phisherman wrote:

I'd go with this one too. Put a bucket of water on the lawn, wait an hour then lay the board where the water was. Wait till the board flattens then remove it. Lay it flat until it dries.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Markndawoods wrote:

Find yourself a good, flat surface, dampen the convex side (not dripping wet, just a fine spray works) and pile on bricks or sandbags, whatever you have around, until it dries and flattens. It may never be completely flat, fair warning, but it will take out the majority of the bend. If you can get it down to a nearly acceptable level, mount it concave side up and you can hold down the perimeter with a few well-placed nails or maybe even double-sided tape, depending on the amount of bend you still have.
Unless you have a really good reason not to though, it'll be faster and easier to just go get yourself another piece of hardboard, they're cheap at any home center.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Seems to me wetting the convex side would worsen matters. Typically the material bows in on the dry side.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Leon wrote:

You're right, I should have said concave side, although wetting both probably doesn't hurt either. The way he described it didn't seem to me to be a problem with wetness, but with leaning against a wall unsupported so that gravity was responsible for the problem.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I actually would not suggest wetting at all but apparently the damage is done and it is not much of a loss either way. My experience with this compressed wood product stuff is that once it gets wet it swells and stays that way. Now warped ply wood would possibly be another matter concerning wetting it down.
Last eeek Swingman and I were building kitchen cabinets and we had 1/4" oak plywood leaning against a fence, in the sun, for about a half day. It warped pretty badly in a mattter of a few hours. IIRC the next day he put more plywood in the shade with no ill effects.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

My father (a carpenter and joiner all his working life) told me that to get hardboard to go flat you should dampen the backside of it just before you use it and then pin it down. As it dries, it shrinks slightly and pulls itself flat.
Hope this helps Micky
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.