Email digest for the Global Conservation Forum (ConsDistList) egroup. ------------------------------------------------------------------------------------------------------------
1. RE: Hanwell RH and T sensors and VOCs ------------------------------------------------------------------------------------------------------------ 1.From: Kim Hewitt Posted: Saturday January 25, 2025 8:37 AM Subject: RE: Hanwell RH and T sensors and VOCs Message: Hi Sarah, If you can safely raise the temperature of your case incrementally 5 degrees , you may be able to clear the humidity issue enough to return to your standing target of 50 degrees relative humidity. Hope all goes well, Kim E Hewitt ------------------------------ Kim Hewitt Brooklyn United States ------------------------------ ------------------------------------------- Original Message: Sent: 01-24-2025 08:21 From: Kim Hewitt Subject: Hanwell RH and T sensors and VOCs The sensor has picked up a sensitivity within the case. Possibly the light source for this case and how is it run and positioned. ------------------------------ Kim Hewitt Brooklyn United States ------------------------------ Original Message: Sent: 01-23-2025 11:40 From: Sarah Coggins Subject: Hanwell RH and T sensors and VOCs Hello conservation community We have two Hanwell RH and T sensors inside a showcase that are reading an RH of >75%. The temperature readings are in an acceptable range of 19-21 degrees centigrade. We cannot determine the cause of the high RH, the small HVAC systems in the case are turned off and isolated and there is no source of water anywhere near the case. The RH in the gallery is low, at around 30-40% although the case is well sealed at 0.23 air exchanges/ day. I have also put a good quantity of silicag gel in the case that has not brought the RH down as would be expected. Equally in the past when cases have had high RH there has been condensation on the interior of the cases and this is not visible on the case in question. The objects inside the case are regularly monitored and we have seen no changes or degradation that would be expected if the RH was in fact >75%. I have replaced the sensors in the case with ones from a very stable area that maintains 55% RH and the sensor quickly read the same high RH but when I put it back in the area with a constant RH of 55% the RH reading has not come down in line with the other sensor in the area. Does anyone have any experience of this happening in their collection? I think I heard once that VOCs can have an effect on the accuracy of RH sensors but I can't remember where I heard that. There may be painted MDF in part of the display mounts or on the objects may be off gassing. I would love to hear your ideas or advice. Thank you ------------------------------ Sarah Coggins Conservation Engineer Mary Rose Trust Southsea United Kingdom ------------------------------ You are subscribed to "Global Conservation Forum (ConsDistList)" as [email protected]. To change your subscriptions, go to http://community.culturalheritage.org/preferences?section=Subscriptions. To unsubscribe from this community discussion, go to http://community.culturalheritage.org/HigherLogic/eGroups/Unsubscribe.aspx?UserKey=d16eaa87-0f69-494b-9f2f-303dbc1222e1&sKey=fab9aa4f27a04c5d876e&GroupKey=757a8f16-505f-4323-8e74-e376757aa9f7.
