Calibrating & Re-Certifying X-Rite Densitometers

[Chris]

I want to get a general concensus on calibrating X-Rite densitometers. We have about 4 or 5 in the plant and the cost to recalibrate is crazy! Under our ISO Quality Standards we have been calibrating these devices annually. How often does +your+ press room calibrate and re-certify their densitometers?

Thanks.

 

[meddington]

Re: Calibrating & Re-Certifying X-Rite Densitometers

Recertification is often unecessary, and for ISO 9000 purposes, you really only need to verify the device is performing at an acceptable level, not necessarily recertify. There's a couple of ways you can achieve this. One would be to recertify one instrument, than use this to verify performance of the other instruments. If all other devices measure the same, within say 0.02 density for the appropriate filter, you could delay recertification. Another option is to purchase the T-Ref card from printtools.org and use this as your reference for all instruments. If all instruments measure within tolerance, your good to go. In both cases, documentation and an annual verification schedule would be necessary to conform with ISO 9000.

I implemented "re-certification-free" procedures for all our in house spectrophotometers and densitometers here....saved the company about 3-4K per year in re-certification costs, only recertifying the instrument when necessary. This is actually better than simply recertifying the instrument annually as we now have documentation that shows unequivically how each instrument performs compared to all others.

 

[meddington]

Re: Calibrating & Re-Certifying X-Rite Densitometers

Oh yeah, its important to understand the difference between calibration, verification, and recertification. Calibration of a densitometer should be taking place quite often...daily of before each use. Verification on the other hand, can be scheduled out in longer time frames. Recertification is not a requirement of the ISO standard, but is usually assumed to be a necessity...and as you pointed out, not an inexpensive one at that.

 

[larrysison]

Re: Calibrating & Re-Certifying X-Rite Densitometers

Hi Chris,

I think...there's no clause in ISO 9001:2000 which states that recertification of ALL instruments is a must. From what I know, it is up to the organization being audited to mention which processes, devices, materials, etc... they would want to strictly monitor to make sure all critical to quality parameters (CTQs) are met.

Michael is correct to suggest and just re-certify one instrument, to use it as a master device so you have something for the other similar devices to compare your readings with.

My thoughts only.

Larry P. Sison
Alyaum Printing Complex
Dammam, Saudi Arabia

 

[Paultheprinter]

Re: Calibrating & Re-Certifying X-Rite Densitometers

will the white patch on the t card from printtools.org be ok to calibrate absoloute zero when reading LAB refs. I looked at the website and the only one which mentioned suitability for LAB was the most expensive and had lots of secondary colours which i dont need, As im going to buy it myself would the basic t card do.

Cheers Paul

Edited by: Paul Green on Jan 10, 2008 7:33 AM

 

[meddington]

Re: Calibrating & Re-Certifying X-Rite Densitometers

>will the white patch on the t card from printtools.org be ok to calibrate absoloute zero when reading LAB refs.

Are you talking about measureing Lab or density and relative to the paper (removing paper white) or absolute white (measureing with paper included)? For Lab measurements, you would not want to calibrate the spectro relative to the paper (remove paper white). For one, most spectros probably won't allow this, and second, your readings would surely be skewed from the Lab benchmarks provided with the card. Lab readings relative to paper are not easily calculated as paper is a large influencing factor in color.

Therefore, purchasing the T-Ref card for verifying Lab measurements isn't advisable as 1) there are no provided Lab values with the T-Ref card, just density (absolute density at that, that is, including paper), and 2) since there are no Lab values, there is no tracebility back to an official standard (ANSI) for verification.

 

[Paultheprinter]

Re: Calibrating & Re-Certifying X-Rite Densitometers

Thanks for the reply, i want to measure LAB to check my ISO compliance, but my colometer/densitometer has not been re calibrated or re certified in over two years, when i take LAB measurements i should zero to "absoloute zero" at least twice a day (according to the manual). But i dont have a abs patch to ref to, i was hoping that the white patch on the t card served this function. As in it was +100 on the L and 0 on the A and B channels.

Have i missed the boat? Sorry i keep calling it a densitometer force of habbit.

 

[PeterA]

Re: Calibrating & Re-Certifying X-Rite Densitometers

Chris - do,what everyone does (apart from me - fudge it - you have 5 of them as long as they all measure the same its no probelm - The real problem is when clients ask for certificates - I have negotiated with the company tthat I bought them from to come in once a year to calibrate them

peter

 

[meddington]

Re: Calibrating & Re-Certifying X-Rite Densitometers

>Thanks for the reply, i want to measure LAB to check my ISO compliance, but my colometer/densitometer has not been re calibrated or re certified in over two years, when i take LAB measurements i should zero to "absoloute zero" at least twice a day (according to the manual). But i dont have a abs patch to ref to, i was hoping that the white patch on the t card served this function. As in it was +100 on the L and 0 on the A and B channels.

You're saying you don't have the ceramic or cardboard reference for calibrating the device then, right? I wouldn't recommend using the white patch on the card. Depending on the device the results might not be significantly impaired, but I'm not in a position to say they wouldn't. What device are you using?

 

[Paultheprinter]

Re: Calibrating & Re-Certifying X-Rite Densitometers

Yes,i need a new card with which i can re-calibrate the device. The company brought the vipdens 2000 about five years ago, we had a contract to calibrate them once a year but this has not been updated recently, i still have what i think is a t card it has C,M,Y,K and a white "ref " box, but they were valid until may 04. I thought most spectrophotometeres had to be calibrated or zeroed to a white point at least once a day to ensure accuracy of the results? i have e-mailed a few companies asking if they do a absoloute white T card but i have had no reply. Does such a thing exist?

Paul

Edited by: Paul Green on Jan 11, 2008 12:52 PM

 

[meddington]

Re: Calibrating & Re-Certifying X-Rite Densitometers

If the card you have is well cared for, it could still work as expected..being that its out of its certification period, nothings guranteed though. PrintTools.org does provide T-Ref cards for Xrite devices, and they could be simlar to what you need, but you might be better off getting it from your device's manufacturer. That it and of itself, doesn't constitute re-certification of the device however.

 

[jlind]

Re: Calibrating & Re-Certifying X-Rite Densitometers

Paul:
Besides a T-Ref, there is also a LAB-Ref, for your spectrocolorimeter. Also from IDeaAlliance.
John Lind
Cranberry Township, PA
724-776-4718

 

[Paultheprinter]

Re: Calibrating & Re-Certifying X-Rite Densitometers

Thanks for the heads up,

Just read the speel and it says paper white in its tech spec, i think i need an absoloute white. I assume the two are different as if i zero to paper white then my readings will be relative not absoloute and the iso standards are absoloute density i.e paper included ( as mentioned above ) The old card has yellowed over time, i recalibrated to absoloute zero on ref patch then measure a standard 130 silk and it came up L 100.9 A 2.7 B 0.3 which must be wrong.

Edited by: Paul Green on Jan 11, 2008 3:19 PM