Solvent pop, runs. Single Stage and fixing the issue.

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PostPosted: Mon Jul 17, 2017 11:00 pm
Hey guys,
Couple quick questions for everyone.
I am a complete novice at autobody/paint. I am currently working on an old Honda motorcycle and just finished spraying it. For my first time spraying I am fairly satisfied with how the process went, not perfect by any means but it passes the 5 foot test. I tend to be pretty hard on myself and like things to come out as good as I can get them. After laying down the final coats of paint, there are certainly some imperfections. I would like advise on how best to fix them.

Important information:
The paint is single stage paint. The primer went on pretty smooth and is a 2 part primer. No sealer. Paint was reduced at the jobber and I added "standard" hardener. For the most part the paint went down slick and pretty good.

The issues:
1. There are some serious runs resulting in "drips" formed at the bottom of some hard edges.

2. There is some "pop" on the sides of the gas tank, I am betting it is a result of my impatience and not waiting long enough for it to flash off. The "pops" are VERY small, but are in several concentrated areas.

My questions:
Can I wetsand and then cut/buff these out? If so, what is the recommended procedure?

If not, how should I go about sanding down the areas to prep for fresh paint to be laid down? I would rather just repaint the concentrated area as opposed to the whole piece if at all possible. Paint is running out and so is my budget.

Is it acceptable to simply sand down the area with the imperfections, get it smooth, and just shoot it the single stage on top of that, or must I reapply the primer again?

Thank you for any help.

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PostPosted: Tue Jul 18, 2017 9:14 am
Post some pictures please.
Is this a metallic or solid color?
1968 Coronet R/T


ACTS 16:31



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PostPosted: Tue Jul 18, 2017 2:09 pm
Solid Color. Will attempt to upload some photos, but it is nearly impossible to get a picture of the "pop"

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PostPosted: Wed Jul 19, 2017 9:02 am
SOLVENT POPPING
(Boiling, Blowing)
Small bubbles, pinholes or crater-like openings in or on the paint film.
____________________________________________________________________________
CAUSE_____________________________________________________
(A) Liquid solvent (thinners/reducers) becomes "trapped" in the paint film when the surface layer skins over too quickly, preventing their evaporation into the atmosphere. Solvents that vaporize within the paint film leave bubbles, pinholes or craters as they push through and "pop" the surface.
Solvents can be trapped due to:
(1) Thinner/reducer evaporating too fast for spraying conditions;
(2) Inadequate flash time between coats;
(3) Excessive film thickness or "piling on" of heavy/wet coats;
(4) Too much air movement causing surface to "skin over" before solvents evaporate;
(5) Excessive purge/flash time before force drying.
REPAIR _________________________________________
(1) Allow finish to thoroughly dry/cure, sand smooth and refinish. Inspect surface
carefully to ensure all craters have been removed.
(2) Severe popping will require removal of the affected film. Prime, seal and recoat,
as necessary.
PREVENTION______________________________________________
(A) Select recommended thinner/reducer based on temperature, humidity, air movement and size of repair;
(B) Allow for proper flash time between coats.
(C) Avoid "piling on" or double wet coats.
(D) Restrict air movement over the surface being painted.
(E) Avoid extended purge/flash time before force drying.

NOTE: Fine dust particles that fall on a tacky surface can be encapsulated by the wet film, creating an appearance almost identical to solvent pop. This "solvent pop" appearance
usually occurs on vehicles that are removed from the booth in a somewhat tacky condition and placed in another location to dry.
Fine dust contamination can be removed by sanding and polishing. However, If the condition is solvent pop, the finish will contain pinholes or small craters after being sanded.
1968 Coronet R/T


ACTS 16:31

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