1 Topic by bbriggsgeek

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Topic: Natural ABS coming out Grey

I'm extruding GP35 ABS at 190 degrees and it's coming out grey.  At first I just thought there might be some residual colorant in the barrel but after several hours it's not getting lighter.  This has happened before with PA747.  I've been trying several different vendors/formulas for ABS.  It doesn't happened all the time.  I recently got some (don't know the formula) from Push Plastic and that didn't get as dark but was slightly grey.

I've read where this can be cause by extruding too hot but 190 shouldn't do that, should it? 

I do use ASACLEAN to clear out any remaining colorant between batches.

I haven't printed with this batch yet but I didn't have any trouble bringing with the grey stuff before.

2 Reply by elmoret

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Re: Natural ABS coming out Grey

Natural doesn't have any colorant, so it will pick up the slightest thing - could be excessive head, leftover asaclean, carbonization, etc. If you want truly white filament, you need to add white colorant.

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3 Reply by bbriggsgeek

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Re: Natural ABS coming out Grey

I like the off white of natural.  That is what I'm shooting for. 

should I try a new barrel?

4 Reply by IanJohnson

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Re: Natural ABS coming out Grey

It is possible that your heater band is a little too far from the nozzle.  That would require a higher temp in the melt zone to reach 190 at the nozzle.  Also running a slightly lower temp for purging will help.  I find that when the plastic is more melted, it can slide past what is already in the barrel rather than drag it out.

5 Reply by Ggalisky

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Re: Natural ABS coming out Grey

IanJohnson wrote:

It is possible that your heater band is a little too far from the nozzle.  That would require a higher temp in the melt zone to reach 190 at the nozzle.  Also running a slightly lower temp for purging will help.  I find that when the plastic is more melted, it can slide past what is already in the barrel rather than drag it out.

Do you encounter plastic sliding by when purging from material to material, or changing colors?

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6 Reply by IanJohnson

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Re: Natural ABS coming out Grey

That was going from ABS to PLA.  At higher temps the PLA would run clear, as the temp dropped bits of burnt ABS would begin to appear in it.  This was before the melt filter, I guess with the melt filter that stuff would still be kicking around in there.  I don't know if anything stuck to the filter would have much ability to color whatever was being extruded.