Blue marks on maple with water based varnish?

[carlb40]

Hi guys.

I made a maple/purple heart mallet last week. After waiting for the purpleheart to go back to purple after machining. I finally got to apply a coat of varnish the weekend.
It was sanded up to 600g (wet & dry paper ), dampened to raise the grain. Left over night to dry. Sanded with 800g wet and dry paper. Dusted off and then coated with B&Q own brand satin waterbased varnish.

Last evening i looked at the mallet head and noticed there were blue streaks on the maple Before and during the varnishing, the maple showed no evidence of staining.

So this morning i sanded it all off using 120 - 180g papers

Any idea what caused it, and how i can stop it happening again?

 

[marcros]

blue staining sounds a bit like either a drying/seasoning error, or a reaction with something like chainsaw oil. Presumably other light coloured timbers could show similar things. I have seen it on pictures of holly, although I am not hugely experienced. I would have thought that you would have seen it prior to finishing though.

Could it be dust from the ph getting into the maple, although blue is a mystery? have you used anything blue during the process- brush, paper etc?

 

[CHJ]

You say you used wet and dry abrasive, what oxide was it? is there a chance you are getting a staining from a reaction between wood acids/water/abrasive.

Blue staining can also occur from a fungal infection in wood when exposed to damp, although I would be surprised at such a rapid showing even though wet sanding will have increased the surface moisture content considerably.

 

[carlb40]

Hi Marcros

There was nothing oily around me or on me while sanding/varnishing. Also there was nothing blue used either to wipe/ dust off the maple.
Not sure if it would effect it? As they are recommended for water based finishes, i used a foam brush for applying the varnish?

 

[carlb40]

You say you used wet and dry abrasive, what oxide was it? is there a chance you are getting a staining from a reaction between wood acids/water/abrasive.

Blue staining can also occur from a fungal infection in wood when exposed to damp, although I would be surprised at such a rapid showing even though wet sanding will have increased the surface moisture content considerably.

The wet and dry is from halfords. Not sure it mentions a brand name on it.
Think with the next coat of varnish i will leave out the initial wet and dry steps until the 1st coat of varnish is applied?