Working with 3mm Hardboard

[Damian Stevenson]

My current long-running creative project involves mounting things on bases made from 3mm hardboard – a material I selected on the understanding that it doesn’t warp. This has proved to be incorrect, and my first two pieces are now rather wobbly and unprofessional-looking as a result.

Does anyone with a lot of first-hand experience of working with the stuff know of a way to un-warp hardboard? I can't subject it to pressure, as that would destroy the things mounted on it.

How about a way to prevent future pieces of hardboard warping like this? Unfortunately I am stuck with it, and cannot switch to another material this late in the project.

[Benjamin Crowe]

How big are the pieces of 3mm? If they are not too big you could try getting them damp then vac bagging them to a known flat surface. I don't know if this will work just an idea.

[Damian Stevenson]

The biggest one is about 13" by 9". I had some larger pieces planned, but the project is effectively cancelled until I can resolve the warping issue.

[Iain Sharp]

Yep. Hardboard is not a stable material at all. If you make sure it is dry and then keep dry at a stable temperature then it might stay flat if the pieces aren't too big. If it gets wet or put in a humid area then it will degrade quickly. 

Iain

Sent from a mobile device.

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[Joe Duckhouse]

Moisture causes hardboard to warp. 

Did you use a water based paint or glue on the mounted side?

Easiest way to un-warp hardboard is to make it warp the other way. 

Wet a cloth and wipe it on the other side then let it dry. 

Sent from my iPhone

On 15 Dec 2013, at 14:31, Damian Stevenson <shallo...@gmail.com> wrote:

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[Damian Stevenson]

Unfortunately I was led to believe that hardboard was the ideal material because it doesn't warp. This, incidentally, is why I prefer first-hand advice (where available) over what some random Google results throw up.

Yes, I have used both water-based glue (PVA) and paint (acrylic, in four colours) on the top side. I am currently engaged in attempting to warp it back the other way. Water had no discernable effect, so I tried watered-down PVA. That improved things noticeably, but still wasn't a "fix". I am currently trying neat PVA glue.

For future pieces, do you think somehow sealing the board with varnish or PVA or somesuch would eliminate warping?

I am sure I've seen similar projects using identical materials with no warp. I would love to know how they have achieved that.

[Bob Clough]

Did you paint both sides? If not, each side will absorb moisture at
different rates, causing warping.

From my experience with MDF, I'd'd suggest making sure any pieces you
want to be dimensionally stable are completely sealed in an oil-based
paint or waterproof varnish. Yacht varnish is my favourite.

[Damian Stevenson]

Sadly not. I was led to believe that it would not warp, so all the glue, paint and mounted objects are on the one side.

I am attempting to correct the warp of the two pieces I'd thought were finished by plastering the other side with PVA and hoping the contraction will correct the warp and stop them wobbling.

Thank you for the recommendation of yacht varnish! I believe that I have seen that in Wilkinsons. Does it being oil-based make that much of a difference? Surely the liquid will still get into the fibres and cause the warping problem.

[Damian Stevenson]

I am attempting the yacht varnish trick this evening. I shall keep you all posted as events warrant.

[Damian Stevenson]

Well, the first coat of yacht varnish has caused the hardboard to warp by itself. So much for that idea.

I wonder if polyurethane spray varnish might do the trick instead? Unfortunately that brings us right back to my other problem about using the spray booth in this weather.

[Damian Stevenson]

I have borrowed a bit of 3mm plywood offcut from the space and have painted one side of it in glue to see if it warps.

[Damian Stevenson]

I can now confirm that the 3mm laser-grade plywood also warps.

I'm running out of options now. Cork tiles and MDF are the next things on the list to test.

[Mellchie]

Have you tried painting both sides at the same time and standing on edge? I can't see a post from you saying you have?

Also, I read from above that you're using water-based paints. Have you tried something spirit-based, applying a thinned-down layer to both sides (at the same time) to seal? I suspect 3mm [anything not plastic] will warp if you only ever apply to one side.

[TeamWild]

This might be a silly question but does it have to be wood? You could use 3mm perspex. Painting just requires a light sanding as a key and a primer coat.

On Sunday, 15 December 2013 14:31:24 UTC, Damian Stevenson wrote:

[Damian Stevenson]

3mm hardboard was the material in which I invested in the mistaken belief that it would be suitable.

I have never worked with perspex before. How much does it cost? Does it warp? Does it require specialist tools to cut? How harmful is the dust? Can it be shaped so it has rounded edges? What thicknesses are available?

[Mellchie]

Cost? Depends. Have a look at Kitronic, trent plastic and theplasticstockist's websites for an idea of what's available and their respective prices. If you buy laser grade you can achieve a much cleaner, replicable (and potentially faster if you cut multiple)piece (you'll need a laser induction, though).

Unless you're planning to expose to strong light or repetitive heating/cooling, I'd say perspex is a stable product. Don't know if it can be painted to a suitable finish, but it comes in so many colours/finishes I personally wouldn't bother. Can be cut with normal tools - I've never heard of anything needing specialist kit because it's plastic. Will it take a rounded edge? Probably, but wirth experimenting with. If it does work you could probably get a realy nice finish if you flamed it afterwards.

Dust? Again, I don't particularly know anything about the respective dangers of plastic/hdf/etc. dust but I wouldn't want to inhale any of them. I suspect the same precautions should be taken for both and I would start with a mask and vacuum cleaner.