I’ve been really enjoying the beauty of the silk filaments, whether Bambu brand or others. However, what I’m finding, is that they are not very strong.
Specific applications I’ve tried to print are the articulating dragons/basilisks that have the ability to lock. When I print them in a standard or matte filament, they are strong enough to lock and de-lock frequently and have no issues. When I use the silk filament, although visually fantastic, they are not strong and break upon attempting to un-lock.
Does anyone have recommendations for strong multi-colour filaments? They don’t have to be silk, but just multi-colour would be great. Thanks!
I had an issue with a Looney tunes character needing a silk silver appearance for the gun barrels. The Bambu silk was probably the worst I used for strength. I used Filamentum brand and it turned out to be the strongest of four different silk silvers that I have. I don’t know if other silks they have are as strong but I’m sure it’s the polymers and other additives that companies have to use to produce the shine that weaken the pla. Hopefully this is helpful and you need silver because I would recommend this one.
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I only tried one brand so far as I have no big need for silk.
But I also have the habit of calibrating and fine tuning every new type or color of filament I add.
With the silk I noticed that the usual print speeds and temps won’t really work as planned.
For obvious reasons one tunes those filaments for THE BEST VISUAL appearance.
At least for the filament I had that meant it was from ideal in terms of getting the strongest possible bonds or impact strength.
And if tuned for best strength resulting in a bad look the parts are still weaker than standard PLA.
The issues get far worse the smaller the printed part or area of the print is.
I printed a little statue and within seconds of my niece playing with it the legs broke off.
Printed in standard PLA I required a lot of force to do the same…
I all fairness though I have similar issues at a lower degree with a lot of temp sensitive filaments.
Whenever the extrusion temp is a factor for the visual appearance it seems that it comes at the price of strength, flexibility, ductility or simply layer adhesion.
With the last about 20m of the silk I tried some testing…
I had the temps for good strength and best visuals…
So I ignored the later and went for best results at the expense of the shiny silk look.
Once printed I placed the part (a torso in vase mode) into the freezer.
Using a little blow torch and SOFT flame I then tried to get the required shine.
Turned out a single wall and hollow object does not retain the frozen state for long so I had to work fast.
The result was neither even nor perfect but in some areas I got the required shine and appearance.
One major issue was that the carbon from the flame reacted with the filament and resulted in unwanted changes of color and brightness.
With this little success I tried again using a bigger model and a HEAT GUN.
Ever tried to ‘carve’ something out of ice using a flame or heat gun ???
Takes time to learn how to do it properly, same on filament…
After a lot of failures and with little filament left I managed to find a good balance.
Give it a try with some model that does not use much filament:
Use some tape on the model and some wooden board to glue the model to the board.
Meaning you apply the glue on the tape not the model 
Ideally you can place it on some lazy susan to make the turning easier.
Using a thick dowel with a flat end to stick the model on works best if you have to get the heat onto the model from below as well.
Find a distance that works best for you and to reach all areas of the model evenly.
Then grab a length of filament you hold at this distance and start blowing and moving.
Crank the heat up until you need to make quite fast passes to prevent the filament from getting too soft that it starts flicking down.
If it slowly gets soft and starts bending down evenly you found the right rhythm and temp.
Now do the same on you model and use a strong light close by to notice the change on the surface.
Try do it all in one go and avoid having to go over already shiny areas again.
Are there downsides?
Many, especially if don’t have a heat gun, so don’t buy one just to try…
It only works for filaments that require a HIGHER print temp to get the shine while the best strength is reached at a lower temp.
Thin parts of a model are tricky to impossible as you risk sagging, bending or worse.
It won’t work the first time, try some quick and simple models and if this won’t work as expected for you forget about it.
If you do get improving results keep going and hone your skills
Those heat guns for de-soldering work of SMD parts offer a much better temp and airflow control.
If a cheap heat gun from the hardware store gives you nice results a de-soldering one is worth to consider for an upgrade.