The Coating and Sealant Conditions Log SOP

Purpose

When a stain blushes, a caulk bead washes out or a coating peels a season later, the first question from the customer, the manufacturer's rep and the shop's own insurer is the same: what were the conditions when it went on? A shop that can answer with four readings, a time and a batch number, taken by a named person at the work, is in a different conversation from a shop that says "it was a nice day." Coating and sealant warranties are generally conditioned on application inside the data sheet's limits, and showing that usually falls on the applicator.

This SOP guarantees a dated record of conditions at the start, middle and last application of every exterior coating or sealant, checked against that product's own data sheet, and it stops work the moment a reading fails. The log that proves you were inside the limits is the same log that tells you when you are about to leave them.

Scope

Covers: any exterior or unconditioned-space application of paint, stain, sealer, caulk, sealant, adhesive or roof coating, by any trade, whose data sheet states a temperature, humidity, dew point or rain limit.

Does not cover:

• Deciding whether the day is a go at all. That call is made before the crew rolls, under The Daily Weather Go/No-Go SOP, and this log starts where that one ends.
• Telling the customer about a hold. That belongs to The Weather Reschedule Communication SOP.
• Meter technique, taught in How to Take a Dew Point and Surface Reading Before Coating.

Roles and responsibilities

The handoff that matters is the second one. A tech who logs a failed reading and keeps working has produced evidence against the shop.

Procedure

1. Build the log header before any container is opened. On the job record, start a conditions log entry and fill the header: each product's name, the batch or lot number printed on the container, and the limits copied from that product's data sheet (minimum air temperature, minimum surface temperature, maximum surface temperature if stated, maximum relative humidity, required spread above dew point, rain-safe or recoat time, and any overnight minimum). Acceptance: every limit field is filled from the sheet, or marked "not stated" after reading the sheet; a blank field means the sheet was not read. Wrong looks like: no sheet in hand, or the container on site is not the product the job specified. Stop rule: do not open the product; call the office to pull the sheet or confirm the substitution, and log the wait. Hazard: read the safety data sheet's flammability and ventilation sections at the same time, and for a solvent-borne product keep ignition sources, including a running generator or heater, away from where it will be opened and applied.

2. Take the start reading at the coldest representative spot of the surface you will work first. Measure air temperature and relative humidity in shade at the work, record the dew point the meter computes, then shoot the surface temperature with an infrared thermometer at the coldest spot on that surface (the shaded end, the low course over cold ground, the side away from the sun). Enter time and initials. Acceptance: air and surface at or above the sheet minimums, surface below any sheet maximum, humidity at or below the sheet maximum, and surface minus dew point at or above the sheet's spread, or 5 F where the sheet is silent. Wrong looks like: any one value outside its limit, including a surface that reads fine in the sun and fails ten feet away in the shade. Stop rule: enter the line marked HOLD, re-read in 30 minutes, and if it still fails at the lead's cutoff, the day is a reschedule. Hazard: never aim the thermometer's laser at anyone's eyes, and take any reading from a ladder with three points of contact, at arm's reach, never leaning out past the rails to reach a spot.

3. Read the hourly forecast through the cure period and write the "last application by" time. From the hourly, note when air temperature is forecast to cross the sheet minimum, when it is forecast to reach the dew point (dew starts settling then), and the first hour with meaningful rain probability. Subtract the sheet's rain-safe or dry-to-touch time from the earliest of those three hours. That time is the last application by, written on the log and said to the crew. Acceptance: a clock time is on the log, and the remaining scope fits before it. Wrong looks like: the scope does not fit. Stop rule: the lead reduces scope to what finishes before the time, and the rest goes to the office as unfinished scope; nobody works past it to finish an elevation. Hazard: if the hourly carries thunderstorms, the crew works under The Lightning Stop Work SOP as well, and its stop overrides this one.

4. Take the midday reading where the work is happening. Around midday, or halfway through the scope, repeat all four readings at the surface being worked, and note whether dew point is rising or falling since the start. Acceptance: all limits pass, and the spread is not closing faster than the forecast suggested. Wrong looks like: dew point climbing while air temperature has already peaked, which shrinks the afternoon. Stop rule: the lead moves the last application by time earlier and tells the crew which surfaces drop off the day. Hazard: sun-loaded metal and dark surfaces can exceed a sheet's maximum surface temperature and burn bare skin, so read before touching and wear gloves on hot flashing.

5. Take the last-application reading before the last application, at the surface that will get it. This reading goes at the surface and elevation where the final bead or coat will land, which is often the shaded side worked last. Acceptance: all limits pass. Wrong looks like: a late-day surface already near dew point, typically the north or shaded side once the sun is off it. Stop rule: stop work on that surface, leave the joint open or the section unpainted rather than finish it out of limits, log the stop time and reason, and tell the lead before packing up. Hazard: late light makes ladder footing and roof edges harder to see, so ladders come down while there is still light to see the feet and the ground under them.

6. Close the day's entry. Record the application end time, what surfaces were finished, what was left and why, any protection placed (covers, masking left on), and attach two photos: the meter display showing the last reading, and the container label showing product and lot. Acceptance: end time, scope finished, scope left and both photos are on the record. Wrong looks like: "done" with no end time, or no photo of the lot. Stop rule: the entry is not closed until the photos are attached; the lead checks before leaving the site. Hazard: rags wet with oil-based stain or linseed products can self-heat and ignite, so they go flat to dry or into a closed metal container with water, never balled in a bin or the truck.

7. Check the work at the next visit wherever the night broke a limit. If the overnight low crossed the sheet minimum, or rain or dew arrived inside the rain-safe period, inspect before doing anything else: press an inconspicuous spot of the bead or film, and look for washout, haze, softness or streaking. Acceptance: film or bead is firm and uniform, or the check is logged as not needed because no limit was crossed. Wrong looks like: tacky, soft or whitened material. Stop rule: photograph it, log it, and open a rework item; nothing is coated over a failed layer. Hazard: surfaces that carried dew or frost overnight are slick, so walk boards, decks and roofs only after they are dry or with traction suited to the surface.

The record this produces

One header and a line per reading, attached to the job record so it travels with the invoice. The office reads it when a callback opens, the owner when a manufacturer asks for proof of conditions, the lead before deciding whether step 7 applies.

JOB 4471  Exterior trim repaint + recaulk
Caulk: exterior acrylic latex   Lot 23K118
Paint: exterior acrylic         Lot 23J402
Sheet limits (both): air/surf min 40 F, RH max 85,
  spread min 5 F, rain/dew-safe 3 h
-----------------------------------------------------
Time   Loc   Air  RH  DP  Surf Spr  Result   By
9:00   E     50   80  44  51   7    PASS     DL
12:30  S     62   58  47  70   23   PASS     DL
       Last application by: 4:00 (lead TR)
3:30   N     55   78  48  51   3    HOLD     DL
       North stopped, 2 windows left open    TR
10:15  N     57   62  44  53   9    PASS     DL
       (next day, north finished 11:40)

Fields: time, location on the building, air temperature, relative humidity, dew point, surface temperature, spread, result, initials. Temperatures are F, humidity is percent.

Worked pass

Job: repaint and recaulk exterior trim on a two-story house in late fall. Products and limits as in the header above; the 40 F minimums and 5 F spread are the figures on this job's sheets, illustrative of a common water-based product, not a rule for yours.

Step 1: header filled from both sheets the office sent the night before, lots read off both containers. Pass.

Step 2, 9:00: east elevation, worked first. Air 50 F, RH 80 percent, dew point 44 F. Coldest spot on the east wall, the low corner over the shrub bed, 51 F. Spread 51 minus 44 is 7 F, at or above 5. Air and surface above 40, humidity under 85. Pass.

Step 3: hourly showed air holding in the mid 50s until about 5 p.m., falling to 41 F by 6 a.m., no rain for two days, and air reaching the forecast dew point around 7 p.m., which is when dew starts settling. Seven p.m. minus the sheets' 3-hour rain and dew-safe time is 4:00, so the lead wrote last application by 4:00.

Step 4, 12:30: south elevation. Air 62 F, RH 58 percent, dew point 47 F, surface 70 F in sun, spread 23 F. Pass. Dew point had risen 3 F since morning, from 44 to 47, so the lead flagged the north side, scheduled last, as the one to watch.

Step 5, 3:30, the failure: north elevation, two windows left. Air 55 F, RH 78 percent, dew point 48 F. The trim surface, out of the sun all day, read 51 F. Spread 51 minus 48 is 3 F, under the 5 F the sheet requires, even though every temperature was above 40. The tech stopped, logged HOLD at 3:30, and told the lead, who confirmed the stop and left the two windows' joints open and unpainted. A tech judging by feel would have finished: 55 degrees, dry to the touch, half an hour inside the cutoff. The cutoff is a forecast; the reading is the surface.

Step 6: end time 3:30, east and south done, north two windows left, meter photo and both labels attached.

Step 7, next morning: the low had held at 42 F against the forecast 41, above the 40 F minimum. Dew was on the cars at 7 a.m., but the last east and south work had finished before 3:00, more than the 3-hour dew-safe time before dew could form, so no limit was crossed and the check was logged as not needed. The north windows were read at 10:15: air 57 F, RH 62 percent, dew point 44 F, surface 53 F, spread 9 F. Pass, finished by 11:40.

The failing value was the spread, not a temperature, which is why the header carries spread as its own limit and step 5 reads it at the surface getting the last application. Read on the sunny south wall where the crew stood, it would have passed and recorded conditions that did not apply to the north trim. If a dispute opens on the north side, the log shows it held at 3 F and finished at 9 F.

References

• Manufacturer product data sheets and safety data sheets for each coating and sealant applied; the sheet's own limits override the general 5 F convention.
• See related: The Surface Five Degrees Above Dew Point Rule for Coatings
• See related: How to Take a Dew Point and Surface Reading Before Coating
• See related: Reading a Forecast for the Work, Not the Weekend
• See related: The Daily Weather Go/No-Go SOP