Which resin to fill letters in a sign?

[PerryGunn]

I've got to make a wooden sign for use outside - the sort with routed out letters in a solid piece of wood.

I've got a nice piece of 35mm thick oak that I can use along with letter templates for the routing. Ideally, once routed, I'd like to fill the letters with a coloured resin before sanding the wood and resin back to a nice smooth finish and will likely finish the sign with teak or tung oil to add a bit of weatherproofing.

I believe that, to stop the resin breaking free, I should be routing the letters with a flat bottom rather than a curved one and, potentially, I could make a final pass around the the letters with a dovetail bit to help the resin 'lock' into the wood

I have a couple of questions that I'm hoping someone can help with...

- What's the best sort of resin to use for this sort of application?

- How deep should I route the letters?
The oak is 35mm so I was thinking 17/18mm i.e. half the depth of the wood but that's just a gut feeling, I don't know that's too deep or not deep enough.

Thanks

Perry

 

[Bigegg]

I recommend epoxy resin, although it's significantly more expensive:

I made a "river" table with polyester resin, and the resin was quite brittle, and didn't bond to the timber at all: it basically fell off in one big lump and shattered.

Having said that, cheap polyester roofing resin can produce some nice opaque effects - if a little "pastel" in shade. Maybe a backing layer of untinted, then a top layer of clear? It should lock in with a slight dovetail. Be aware there will be some shrinkage.

You will need the correct pigment, depending upon which resin you use: polyester will tint with (good!) artist type oil paints. (not cheap poundshop ones: they don't have enough pigment) - "Windsor and Newton" *paint* works OK - their drawing ink _doesn't_

https://www.mig-welding.co.uk/forum/threads/brass-swarf-and-resin-casting.88622/
has some pics of stuff I've done in resin.

 

[Bigegg]

PS: I dont think you'll need much more than 6-10mm maximum, depending upon the effect you are after.
You might have issue with cure if you try to go deeper. Try some experiments first!

 

[PerryGunn]

Thanks Bigegg, I'll only have to fill 9 letters (think they're 75mm high) and I'll keep them below 10mm deep so I'll have a look at epoxy - if it's too expensive I'll go for the polyester.

I wanted to dye the resin black so I guess I'll see if I can pick up a small tube of the blackest black I can find

As you say, I'll have to experiment a bit

 

[ecokestove]

Jackson's Art Shop sell Mixol black 20ml for £1.74. It's very intense.

 

[pe2dave]

This setup - as seen, an excellent product and process. Made for the job.
Yep, expensive. They do small 'bottles' which may be OK for you.

 

[AFFF]

I watch a lot of boat building videos on YouTube. Most of them based in the USA. They all seem to use a lot of Total Boat products who supply a very extensive range of epoxy products. Can you buy this stuff in the UK?

 

[Bigegg]

I watch a lot of boat building videos on YouTube. Most of them based in the USA. They all seem to use a lot of Total Boat products who supply a very extensive range of epoxy products. Can you buy this stuff in the UK?

"West Systems" is the UK marine approved equivalent, I believe.
For this job, especially as it's getting pigmented, poundshop Poxy would be OK, I would think.

 

[Bigegg]

Thanks Bigegg, I'll only have to fill 9 letters (think they're 75mm high) and I'll keep them below 10mm deep so I'll have a look at epoxy - if it's too expensive I'll go for the polyester.

I wanted to dye the resin black so I guess I'll see if I can pick up a small tube of the blackest black I can find

As you say, I'll have to experiment a bit

I don't know if oil paints will work with epoxy: I've only used them with polyester!

You *could* paint the letters black, then fill with clear?

Experiment first - yes.

 

[ecokestove]

The thing about Mixol is that it is just a colourant, not a paint, so it has no fillers, oils, dryers etc. I have some and later today I'll try mixing it with some epoxy.

 

[dizjasta]

Hi. Poster paint powdered pigment works well with epoxy resin. It mixes easily has no reaction with resin and a thorough mixing ensures no leaching of pigment when the epoxy has cured.

 

[PerryGunn]

Hi. Poster paint powdered pigment works well with epoxy resin. It mixes easily has no reaction with resin and a thorough mixing ensures no leaching of pigment when the epoxy has cured.

Ah - I wonder if cement dye will work as well, it's a powdered pigment and I happen to have some black left over from pointing a slate path.

Something to experiment with...

 

[ecokestove]

By some coincidence I had made a house name plate last weekend. They didn't want the letters filled, But I did try an experiment with Jesmonite on a gash piece of hard maple with a few letters carved in it, and I've just tried a Mixol/epoxy test on it as well.

The Mixol/epoxy test worked, and produced a nice black letter. However, the resin did bleed into the wood a little. Not much, just a tiny bit and probably wouldn't be noticeable at normal viewing distance. If you used an epoxy liquid I would recommend using a syringe to put it into the letters.

My previous test was done with a product called Jesmonite AC100. This worked very well, and has the advantage of being a water based product that has no smell. Downside is that it's a bit pricey. A starter kit is about £30, unless you buy it via Amazon and then it's a lot more!

I wanted to try Milliput, which is an epoxy two-part putty and comes in black, but mine hasn't been used for some time and had gone off. I'm sure it would work well and you would use it like a two-part wood filler. Amazon has it for £4.49. I think this could be the best solution for you.

 

[PerryGunn]

I wanted to try Milliput, which is an epoxy two-part putty and comes in black, but mine hasn't been used for some time and had gone off. I'm sure it would work well and you would use it like a two-part wood filler. Amazon has it for £4.49. I think this could be the best solution for you.

Thanks - is the Milliput easy to smooth and is it shiny when sanded?

I've been looking at the pourable, liquid epoxies as they will mainly self-level and I can sand down any dome caused by the meniscus. Once flattened, I was thinking of using wet & dry paper (I've got grades down to 7000 grit) then polishing to end up with a shiny finish.

 

[ecokestove]

Milliput is very easy to sand, but I don't know if it will polish. Probably. The thing with polishing with fine grades of wet and dry is that it has to be done wet, and that would then probably raise the grain on the wood. To smooth the wood you would then sand with a dry paper which would spoil the polish on the Milliput. This would probably be the same if you used a liquid resin. Does it have to be shiny?

 

[PerryGunn]

Does it have to be shiny?

It's not essential, I just thought it would look nice - I guess it's something to experiment with...

 

[dizjasta]

Something else that may be a useful colouring to an epoxy filler.

 

[Bigegg]

Milliput, in my experience, won't polish. The filler in it is too coarse/powdery.
It is possible to "laquer" it (for want of a better description) with a thin layer of epoxy which *will* polish.

 

[Bigegg]

Just gonna leave this here...


https://nypost.com/2021/08/25/man-dies-after-having-sex-using-epoxy-adhesive-instead-of-condom/

 

[Fergie 307]

You could try fibreglass resin. Flexible to an extent, sticks like the proverbial and easily coloured and finished.