Ink or Epoxy To Fill Recessed Text on 3D Print

[bostonman]

In the future I may like to add recessed text on a 3D print, but thought filling it with paint or something would make it stand out.

Using paint on a brush to fill in the text would probably be difficult. I was thinking of something watery enough that would self level and dry hard.

The issue I see is using something that will dispense the paint (or some sort of epoxy) and then stop in order to move onto the next letter without making a mess of the 3D print.

Anyone have any ideas?

[ejeffrey]

UV epoxy? Uncured it's pretty thin, and a few seconds with a UV illuminator is enough to set it up enough to keep working.  If you make a mess you can clean it up and try again as it won't cure without UV

CA glue is similarly thin and hardens quickly especially if you hit it with an accelerator.

[bostonman]

Not sure if I've heard of UV epoxy, but it seems ideal.

Having a few different colors would be perfect and only saw clear epoxy on Amazon. Maybe having some basic colors such as black, white, possibly a silver, etc...

This is why I thought paint would be good, but need a way to apply it neatly.

[Kean]

If this is for FDM 3D prints, then you don't want anything that is too low viscosity as it will seep into the cracks and be near impossible to clean up.
Maybe something you can dispense with a blunt needle and syringe?
I am assuming this is low volume not for production quantities.

PS. you can get pigments that can be added to clear epoxy.

[themadhippy]

Maybe have a look at how modelers do things like the  mortar layers on embossed brick work

[bostonman]

If this is for FDM 3D prints

Just to confirm, FDM as I understood it when I searched online, is just basic 3D printing and not the filament type, correct?

If so, then yes, this would be for a standard 3D print (most likely using PLA).

Maybe something you can dispense with a blunt needle and syringe?

I thought of this already and thought it would be perfect, however, I think trying to push vertically on the syringe plunger while trying to fill in the small print would be difficult; especially if I'm under a microscope trying to keep the liquid in the text region.

PS. you can get pigments that can be added to clear epoxy.

I didn't think of this.

Providing the epoxy is liquid enough to flow and self levels but not too thin that it seeps into the 3D printed cracks (as you pointed out), then maybe the initial idea of using UV curing epoxy is the solution. It would also give me a good reason to buy a UV oven, although a quick search for UV epoxy showed they come with a UV light. If I go with UV epoxy, I'll have to research this a bit as I know little about it.

Also, this isn't for production; just one off stuff. In the past I've printed stuff with extruded text. Recently I've wanted to do recessed text, and thought it blend in too much due to being the same color. Filling it with a different color (I think) would enhance it.

[abeyer]

PS. you can get pigments that can be added to clear epoxy.

Alternatively you can do this with the uv resin sold for SLA printers which is sold in all sorts of appearances and colors... one advantage there might be if you care about color appearance you might be able to source your filament and resin from the same vendor with color matched pigments. (Another use case where this is more important, you can also thicken the resin and use it as a top coat over an fdm print to help conceal/fill in layer lines.)

[Kean]

Sorry, yes - I assumed FDM (Fused Deposition Modeling) as that is the most common 3D printing using filaments and extruders, but it is best to clarify if not stated.
Because of the way FDM deposits the extruded material in zigzag patterns and layers it has inherent crevices (and weak spots) in the resulting print.

A resin SLA (Stereolithography) 3D print is still "printed" in layers, but by exposing resin to UV light.  Other popular 3D printing methods may use powder and either laser sintering (SLS) or jet printing of a binder (MJF).  None of these typically exhibit similar gaps/crevices as the material naturally fills the gaps, but SLS tends to be powdery so it also has its own pros and cons.

There are epoxies available in various viscosities, and these can be quite handy to have on hand whether two-part or UV curable.  Clear epoxy plus a few pigments allow you to mix up quite a good range of colours.

As UV resin has a typical shelf life of 6-12 months, a lot of the resin I bought ended up expiring before I used it, so I would probably avoid buying a range of colours again and just mixing pigments on demand.

I never really found SLA 3D printing suited my needs.  I tend to prototype with ABS FDM and them outsource production MJF or SLS prints to JLC.

Model paint can also be use with thinners to reduce the viscosity to potentially make use with a syringe practical, although I've not tried it.  I'd avoid the enamel types requiring solvent, and just use acrylic paint & thinners - unless you have access to glass syringes.

[ejeffrey]

Also, this isn't for production; just one off stuff. In the past I've printed stuff with extruded text. Recently I've wanted to do recessed text, and thought it blend in too much due to being the same color. Filling it with a different color (I think) would enhance it.

Even without a multi material printer you can insert manual filament changes in your slicer at specific layers.  So if you have recessed text on the top or bottom you can insert a filament change to get contrasting text. 

[bostonman]

As UV resin has a typical shelf life of 6-12 months

Oh, that's not good. My intention was to buy something to have on hand should a desire for printing with text arise.

Due to shelf life and application desire such as being watery to flow into the recessed text, resorting to old fashion paint and a very tiny brush applied under a microscope may be the best solution.

[Kean]

As UV resin has a typical shelf life of 6-12 months

Oh, that's not good. My intention was to buy something to have on hand should a desire for printing with text arise.

Due to shelf life and application desire such as being watery to flow into the recessed text, resorting to old fashion paint and a very tiny brush applied under a microscope may be the best solution.

I suspect the shelf life for your usage is probably OK, but could start to cause problems when printing on an SLA 3D printer.
I have some 5 year old resin and it hasn't solidified or anything like many other consumables with shorter shelf life, but I've not tried running my Anycubic Photon-S for ages.

Yeah, I do think the old fashioned paint option is probably just as good a solution but if you can pick up some UV resin cheap it is worth a play.

[Infraviolet]

I've had a go in this scenario by using very watered down acrylic paint (the sort that comes in a toothpaste style tube, then mixed with a lot of water) and trying to drip it in to the recessed letters. Even when very thin it does not leak away through the fine gaps in FDM prints, so long as the initial dripping doesn't spill and you keep the print aligned so the recesses face up until drying is complete, but also it doesn't leave a particularly visible result within the recess once dry. The trouble is once it dries you see that given the paint was very diluted, there wasn't much actual paint within the liquid you poured. So you don't get the recess filled by a solidifed pool of paint, you just get a fine layer within the recess which isn't necessarily hugely visible against the background colour of the printed plastic. I think some people have used some form of nail polish in a similar manner, and got better results because it apparently does act as a runny liquid when wet but then dries to form a solidified lump, of similar volume to when wet, within the recess.

[bostonman]

I think some people have used some form of nail polish

Hmmmm I didn't think about using this. Comes with a small brush and different colors.

Does seem like paint is the best approach to this.

[mawyatt]

We've used Nail Polish in the past for marking/color-coding things, you can thin with acetone. Dollar stores usually have a good supply.

Best

[MarkF]

I would start with thinned paint to flood the grooves.
I expect you would need to apply several coats to get the desired coverage.
It probably isn't possible for very small or thin lettering.

Another thing you might try is ink. 
In my airbrush research, I see that many use ink (especially white) instead of paint.
Apparently white is the hardest color to paint because it seems to dry on the airbrush tip.

[mawyatt]

If you can swap filaments this can produce some nice results. Here we are trying some different filaments (PLA and PETG) as an experiment and to get familiar with PETG filament.

Best

[bostonman]

Those look great, however, the text is extruded, I want recessed.

Although I haven't attempted it, I know a way exists to place a pause in the Gcode to swap filament colors should I want different color extruded text, but I haven't attempted it. Plus, sometimes I don't get lucky and have it feed well, so I'd rather figure out a way to do it on the fly (I've seen videos, but none of them seem quick).

[Berni]

For recessed colored text you have to do 2 filament changes during printing.

1) Print your part with the default filament
2) 1mm before the surface switch to the text color filament and print for 0.5mm
3) Switch back to default color filament and print the last 0.5mm but leave holes where the text color should show.

Otherwise if you want to fill the recessed text you can use UV resin for 3D printers. Pour it on and squeegee across with a plastic card or something, then put in UV to cure. It will however slightly wick into layer seams, not noticeable for weakly colored resins, but might be a problem with very dark colored resins, to prevent that you might have to first lightly paint the part with clear resin, wipe off exess, cure in UV, then apply colored resin. You can also buy just the clear colored resin and mix in pigments yourself, so you only need to buy one bottle but have lots of colors you can mix up on demand in small batches.

[Kean]

Sealing with clear resin should help avoid wicking of the later colour(s) into the gaps, but it may be difficult to avoid filling the recessed text areas with the clear resin in the process.

In the past I have sealed some prints for outdoor use with a couple of layers of acrylic conformal coating spray (Electrolube HPA200H), but I recall it left the print with a finish that I didn't really like.

[MarkF]

Those look great, however, the text is extruded, I want recessed.

Although I haven't attempted it, I know a way exists to place a pause in the Gcode to swap filament colors should I want different color extruded text, but I haven't attempted it. Plus, sometimes I don't get lucky and have it feed well, so I'd rather figure out a way to do it on the fly (I've seen videos, but none of them seem quick).

My Creality CR-10 doesn't have enough firmware program memory to support color changes (M600 - Filament Change command).
I opt'd for other functions more desirable to me.

As old as your printer is, you may have the same issue.  Depends on the build choices and the motherboard.

[bostonman]

Pour it on and squeegee across with a plastic card or something, then put in UV to cure.

This would smear into the sections and wick into areas I wouldn't want though, correct?

Does UV damage the 3D filament such as discoloring it?

I'm a bit torn at the moment because I don't have a project that needs recessed text. If I purchase UV resin for possible future needs, it has a shelf life, so I'd be wasting money since it may go bad by the time I need it. Paint (or nail polish) does seem more logical due to shelf life.

[Berni]

Yes some resin would inevitably end up inside the recessed areas, but you can just wick the majority back out using a paper towel. The resins strong tendency to wick into stuff works both ways. Keep in mind that you don't actually need to get all the resin out, even if you only get 50% of it out that still leaves plenty of a hole for the colored resin to come into (the clear resin sits at the bottom where nobody will see it anyway).

Lots of UV can damage 3D printing filament, but the amount of UV needed to cure resin is way way WAY less than that. Resin hardens in minutes of reasonable UV exposure while it would take more than a day of exposure to deteriorate plastic.

UV Resin does have shelf life, but it is not like it stops working after that time. The manufacturer just doesn't grantee that the properties of the resin are still going to be consistent (like cure time, shrinkage, strength etc..) so that it works reliably in a 3D printer. If you just need it to harden, it can sit on a shelf for a very long time as long as it is sealed well and kept in the dark. You can also buy other forms of UV activated resin that is not for 3D printing. Things like UV cure adhesives that come in a little tube or bottle, there is UV cure soldermask for PCB repair...etc

[tridac]

Paintstick. Used by camera restorers to fill in lname plates, recessed text etc. Just rub it on the surface, allow to dry for a few minutes, then polish iff the surplus. More like a wax than a paint, but used it here for years for old camera work. Microtools used to stock it, various colours as well.

[abeyer]

Paintstick. Used by camera restorers to fill in lname plates, recessed text etc. Just rub it on the surface, allow to dry for a few minutes, then polish iff the surplus. More like a wax than a paint, but used it here for years for old camera work. Microtools used to stock it, various colours as well.

those work great for recesses on otherwise smooth surfaces, but you'll need to do a lot of surface prep on an fdm print, otherwise you'll just smear it all into the layer lines.

[Whales]

I use ordinary crayons, then sand the result back until the excess in the layer lines is removed. 

The only way out of sanding that I can think of is to apply very carefully with eg a hypodermic syringe, but that's fiddly work.